二进制到十进制转换程序-yiteyi-C++库

给定一个二进制数作为输入，我们需要编写一个程序，将给定的二进制数转换为等效的十进制数。

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例如：

Input : 111Output : 7Input : 1010Output : 10Input: 100001Output: 33

建议：请在“上解决” 实践 “首先，在讨论解决方案之前。

其思想是从最右边的数字开始提取给定二进制数的数字，并保留一个变量dec_值。从二进制数中提取数字时，将数字与适当的基数（2的幂）相乘，并将其添加到变量dec_值中。最后，变量dec_值将存储所需的十进制数。例如：如果二进制数是111。 dec_值=1*（2^2）+1*（2^1）+1*（2^0）=7

下图说明了如何将（1010）转换为等效的十进制值：

binary2decimal

以下是上述理念的实施情况：

C++

                         // C++ program to convert binary to decimal                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // Function to convert binary to decimal                       
                         int                                     binaryToDecimal(                                     int                                     n)                       
                         {                       
                                                 int                                     num = n;                       
                                                 int                                     dec_value = 0;                       
           
                                                 // Initializing base value to 1, i.e 2^0                       
                                                 int                                     base = 1;                       
           
                                                 int                                     temp = num;                       
                                                 while                                     (temp) {                       
                                                 int                                     last_digit = temp % 10;                       
                                                 temp = temp / 10;                       
           
                                                 dec_value += last_digit * base;                       
           
                                                 base = base * 2;                       
                                                 }                       
           
                                                 return                                     dec_value;                       
                         }                       
           
                         // Driver program to test above function                       
                         int                                     main()                       
                         {                       
                                                 int                                     num = 10101001;                       
           
                                                 cout << binaryToDecimal(num) << endl;                       
                         }                       

JAVA

                         // Java program to convert                       
                         // binary to decimal                       
           
                         // Function to convert                       
                         // binary to decimal                       
                         class                                     GFG {                       
                                                 static                                     int                                     binaryToDecimal(                                     int                                     n)                       
                                                 {                       
                                                 int                                     num = n;                       
                                                 int                                     dec_value =                                     0                                     ;                       
           
                                                 // Initializing base                       
                                                 // value to 1, i.e 2^0                       
                                                 int                                     base =                                     1                                     ;                       
           
                                                 int                                     temp = num;                       
                                                 while                                     (temp >                                     0                                     ) {                       
                                                 int                                     last_digit = temp %                                     10                                     ;                       
                                                 temp = temp /                                     10                                     ;                       
           
                                                 dec_value += last_digit * base;                       
           
                                                 base = base *                                     2                                     ;                       
                                                 }                       
           
                                                 return                                     dec_value;                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 int                                     num =                                     10101001                                     ;                       
                                                 System.out.println(binaryToDecimal(num));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by mits.                       

Python3

                         # Python3 program to convert                       
                         # binary to decimal                       
           
                         # Function to convert                       
                         # binary to decimal                       
                         def                                     binaryToDecimal(n):                       
                                                 num                                     =                                     n;                       
                                                 dec_value                                     =                                     0                                     ;                       
                                   
                                                 # Initializing base                       
                                                 # value to 1, i.e 2 ^ 0                       
                                                 base                                     =                                     1                                     ;                       
                                   
                                                 temp                                     =                                     num;                       
                                                 while                                     (temp):                       
                                                 last_digit                                     =                                     temp                                     %                                     10                                     ;                       
                                                 temp                                     =                                     int                                     (temp                                     /                                     10                                     );                       
                                   
                                                 dec_value                                     +                                     =                                     last_digit                                     *                                     base;                       
                                                 base                                     =                                     base                                     *                                     2                                     ;                       
                                                 return                                     dec_value;                       
           
                         # Driver Code                       
                         num                                     =                                     10101001                                     ;                       
                         print                                     (binaryToDecimal(num));                       
           
                         # This code is contributed by mits                       

C#

                         // C# program to convert                       
                         // binary to decimal                       
           
                         // Function to convert                       
                         // binary to decimal                       
                         class                                     GFG {                       
                                                 public                                     static                                     int                                     binaryToDecimal(                                     int                                     n)                       
                                                 {                       
                                                 int                                     num = n;                       
                                                 int                                     dec_value = 0;                       
           
                                                 // Initializing base1                       
                                                 // value to 1, i.e 2^0                       
                                                 int                                     base1 = 1;                       
           
                                                 int                                     temp = num;                       
                                                 while                                     (temp > 0) {                       
                                                 int                                     last_digit = temp % 10;                       
                                                 temp = temp / 10;                       
           
                                                 dec_value += last_digit * base1;                       
           
                                                 base1 = base1 * 2;                       
                                                 }                       
           
                                                 return                                     dec_value;                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     num = 10101001;                       
           
                                                 System.Console.Write(binaryToDecimal(num));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by mits.                       

PHP

                         <?php                       
                         // PHP program to convert                       
                         // binary to decimal                       
           
                         // Function to convert                       
                         // binary to decimal                       
                         function                                     binaryToDecimal(                                     $n                                     )                       
                         {                       
                                                 $num                                     =                                     $n                                     ;                       
                                                 $dec_value                                     = 0;                       
                                   
                                                 // Initializing base value                       
                                                 // to 1, i.e 2^0                       
                                                 $base                                     = 1;                       
                                   
                                                 $temp                                     =                                     $num                                     ;                       
                                                 while                                     (                                     $temp                                     )                       
                                                 {                       
                                                 $last_digit                                     =                                     $temp                                     % 10;                       
                                                 $temp                                     =                                     $temp                                     / 10;                       
                                   
                                                 $dec_value                                     +=                                     $last_digit                       
                                                 *                                     $base                                     ;                       
                                                 $base                                     =                                     $base                                     *2;                       
                                                 }                       
                                                 return                                     $dec_value                                     ;                       
                         }                       
           
                                                 // Driver Code                       
                                                 $num                                     = 10101001;                       
                                                 echo                                     binaryToDecimal(                                     $num                                     ),                                     ""                                     ;                       
           
                         // This code is contributed by ajit                       
                         ?>                       

Javascript

                         <script>                       
           
                         // JavaScript program to convert binary to decimal                       
           
                         // Function to convert binary to decimal                       
                         function                                     binaryToDecimal(n)                       
                         {                       
                                                 let num = n;                       
                                                 let dec_value = 0;                       
           
                                                 // Initializing base value to 1, i.e 2^0                       
                                                 let base = 1;                       
           
                                                 let temp = num;                       
                                                 while                                     (temp) {                       
                                                 let last_digit = temp % 10;                       
                                                 temp = Math.floor(temp / 10);                       
           
                                                 dec_value += last_digit * base;                       
           
                                                 base = base * 2;                       
                                                 }                       
           
                                                 return                                     dec_value;                       
                         }                       
           
                         // Driver program to test above function                       
                                                 let num = 10101001;                       
           
                                                 document.write(binaryToDecimal(num) +                                     "<br>"                                     );                       
           
           
                         // This code is contributed by Surbhi Tyagi                       
           
                         </script>                       

输出：

注：该程序只适用于整数范围内的二进制数。如果你想处理长二进制数，比如20位或30位，你可以使用一个字符串变量来存储二进制数。

下面是一个类似的程序，它使用字符串变量而不是整数来存储二进制值：

C++

                         // C++ program to convert binary to decimal                       
                         // when input is represented as binary string.                       
                         #include <iostream>                       
                         #include <string>                       
                         using                                     namespace                                     std;                       
           
                         // Function to convert binary to decimal                       
                         int                                     binaryToDecimal(string n)                       
                         {                       
                                                 string num = n;                       
                                                 int                                     dec_value = 0;                       
           
                                                 // Initializing base value to 1, i.e 2^0                       
                                                 int                                     base = 1;                       
           
                                                 int                                     len = num.length();                       
                                                 for                                     (                                     int                                     i = len - 1; i >= 0; i--) {                       
                                                 if                                     (num[i] ==                                     '1'                                     )                       
                                                 dec_value += base;                       
                                                 base = base * 2;                       
                                                 }                       
           
                                                 return                                     dec_value;                       
                         }                       
           
                         // Driver program to test above function                       
                         int                                     main()                       
                         {                       
                                                 string num =                                     "10101001"                                     ;                       
                                                 cout << binaryToDecimal(num) << endl;                       
                         }                       

JAVA

                         // Java program to convert binary to                       
                         // decimal when input is represented                       
                         // as binary string.                       
                         import                                     java.io.*;                       
           
                         class                                     GFG {                       
           
                                                 // Function to convert binary to decimal                       
                                                 static                                     int                                     binaryToDecimal(String n)                       
                                                 {                       
                                                 String num = n;                       
                                                 int                                     dec_value =                                     0                                     ;                       
           
                                                 // Initializing base value to 1,                       
                                                 // i.e 2^0                       
                                                 int                                     base =                                     1                                     ;                       
           
                                                 int                                     len = num.length();                       
                                                 for                                     (                                     int                                     i = len -                                     1                                     ; i >=                                     0                                     ; i--) {                       
                                                 if                                     (num.charAt(i) ==                                     '1'                                     )                       
                                                 dec_value += base;                       
                                                 base = base *                                     2                                     ;                       
                                                 }                       
           
                                                 return                                     dec_value;                       
                                                 }                       
           
                                                 // Driver program to test above function                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 String num =                                     new                                     String(                                     "10101001"                                     );                       
                                                 System.out.println(binaryToDecimal(num));                       
                                                 }                       
                         }                       
           
                         // This code is contribute by Prerna Saini                       

Python3

                         # Python3 program to convert binary                       
                         # to decimal when input is                       
                         # represented as binary string.                       
           
                         # Function to convert                       
                         # binary to decimal                       
                         def                                     binaryToDecimal(n):                       
                                                 num                                     =                                     n;                       
                                                 dec_value                                     =                                     0                                     ;                       
                                   
                                                 # Initializing base                       
                                                 # value to 1, i.e 2 ^ 0                       
                                                 base1                                     =                                     1                                     ;                       
                                   
                                                 len1                                     =                                     len                                     (num);                       
                                                 for                                     i                                     in                                     range                                     (len1                                     -                                     1                                     ,                                     -                                     1                                     ,                                     -                                     1                                     ):                       
                                                 if                                     (num[i]                                     =                                     =                                     '1'                                     ):                       
                                                 dec_value                                     +                                     =                                     base1;                       
                                                 base1                                     =                                     base1                                     *                                     2                                     ;                       
                                   
                                                 return                                     dec_value;                       
           
                         # Driver Code                       
                         num                                     =                                     "10101001"                                     ;                       
                         print                                     (binaryToDecimal(num));                       
           
                         # This code is contributed by mits                       

C#

                         // C# program to convert binary to                       
                         // decimal when input is represented                       
                         // as binary string.                       
                         using                                     System;                       
           
                         class                                     GFG {                       
           
                                                 // Function to convert binary to decimal                       
                                                 static                                     int                                     binaryToDecimal(String n)                       
                                                 {                       
                                                 String num = n;                       
                                                 int                                     dec_value = 0;                       
           
                                                 // Initializing base value to 1,                       
                                                 // i.e 2^0                       
                                                 int                                     base1 = 1;                       
           
                                                 int                                     len = num.Length;                       
                                                 for                                     (                                     int                                     i = len - 1; i >= 0; i--) {                       
                                                 if                                     (num[i] ==                                     '1'                                     )                       
                                                 dec_value += base1;                       
                                                 base1 = base1 * 2;                       
                                                 }                       
           
                                                 return                                     dec_value;                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 String num =                                     "10101001"                                     ;                       
                                                 Console.WriteLine(binaryToDecimal(num));                       
                                                 }                       
                         }                       
           
                         // This code is contribute by mits                       

PHP

                         <?php                       
                         // PHP program to convert binary                       
                         // to decimal when input is                       
                         // represented as binary string.                       
           
                         // Function to convert                       
                         // binary to decimal                       
                         function                                     binaryToDecimal(                                     $n                                     )                       
                         {                       
                                                 $num                                     =                                     $n                                     ;                       
                                                 $dec_value                                     = 0;                       
                                   
                                                 // Initializing base                       
                                                 // value to 1, i.e 2^0                       
                                                 $base                                     = 1;                       
                                   
                                                 $len                                     =                                     strlen                                     (                                     $num                                     );                       
                                                 for                                     (                                     $i                                     =                                     $len                                     - 1;                                     $i                                     >= 0;                                     $i                                     --)                       
                                                 {                       
                                                 if                                     (                                     $num                                     [                                     $i                                     ] ==                                     '1'                                     )                       
                                                 $dec_value                                     +=                                     $base                                     ;                       
                                                 $base                                     =                                     $base                                     * 2;                       
                                                 }                       
                                   
                                                 return                                     $dec_value                                     ;                       
                         }                       
           
                         // Driver Code                       
                         $num                                     =                                     "10101001"                                     ;                       
                         echo                                     binaryToDecimal(                                     $num                                     ),                                     ""                                     ;                       
           
                         // This code is contributed by aj_36                       
                         ?>                       

Javascript

                         <script>                       
           
                         // Javascript program to convert binary to decimal                       
                         // when input is represented as binary string.                       
           
                         // Function to convert binary to decimal                       
                         function                                     binaryToDecimal(n)                       
                         {                       
                                                 let num = n;                       
                                                 let dec_value = 0;                       
           
                                                 // Initializing base value to 1, i.e 2^0                       
                                                 let base = 1;                       
           
                                                 let len = num.length;                       
                                                 for                                     (let i = len - 1; i >= 0; i--) {                       
                                                 if                                     (num[i] ==                                     '1'                                     )                       
                                                 dec_value += base;                       
                                                 base = base * 2;                       
                                                 }                       
           
                                                 return                                     dec_value;                       
                         }                       
           
                         // Driver program to test above function                       
           
                                                 let num =                                     "10101001"                                     ;                       
                                                 document.write(binaryToDecimal(num) +                                     "<br>"                                     );                       
           
                         // This code is contributed by Mayank Tyagi                       
           
                         </script>                       

输出：

使用预定义函数：

C++

                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         int                                     main()                       
                         {                       
                                                 char                                     binaryNumber[] =                                     "1001"                                     ;                       
                                   
                                                 cout << stoi(binaryNumber, 0, 2);                       
           
                                                 return                                     0;                       
                         }                       
                         // This code is contributed by whysodarkbro                       

C

                         #include <stdio.h>                       
                         #include <math.h>                       
                         #include <stdlib.h>                       
           
                         int                                     main()                       
                         {                       
                                                 char                                     binaryNumber[] =                                     "1001"                                     ;                       
                                                 int                                     bin, dec = 0;                       
                                   
                                                 bin =                                     atoi                                     (binaryNumber);                       
           
                                                 for                                     (                                     int                                     i = 0; bin; i++, bin /= 10)                       
                                                 if                                     (bin % 10)                       
                                                 dec +=                                     pow                                     (2, i);                       
           
                                                 printf                                     (                                     "%d"                                     , dec);                       
           
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by whysodarkbro                       

JAVA

                         public                                     class                                     GFG {                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 String binaryNumber =                                     "1001"                                     ;                       
                                                 System.out.println(Integer.parseInt(binaryNumber,                                     2                                     ));                       
                                                 }                       
                         }                       
           
                         // This code is contributed                       
                         // By Yash Kumar Arora                       

Python3

                         n                                     =                                     input                                     ()                       
           
                         # Convert n to base 2                       
                         s                                     =                                     int                                     (n,                                     2                                     )                       
           
                         print                                     (s)                       

C#

                         using                                     System;                       
           
                         class                                     GFG {                       
                                   
                         public                                     static                                     void                                     Main()                       
                         {                       
                                                 int                                     value = 1001;                       
                                                 Console.Write(Convert.ToInt32(value.ToString(), 2));                       
                         }                       
                         }                       
           
                         // This code is contributed by SoumikMondal                       

Javascript

                         <script>                       
                                   
                         var                                     binaryNumber =                                     "1001"                                     ;                       
                         document.write(parseInt(binaryNumber, 2));                       
           
                         // This code contributed by Princi Singh                       
                         </script>                       

输出：

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