计算一个数字中的总位数-yiteyi-C++库

给定一个正数n，计算其中的总位。 例如：

null

Input : 13Output : 4Binary representation of 13 is 1101Input  : 183Output : 8Input  : 4096Output : 13

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

方法1（使用日志）

n中以2为底的log2（n）对数，它是指数，2被提升到这个指数，得到n个整数，我们在log（n）时间内在一个数字中加1 find total bit。

C++

                         // C++ program to find total bit in given number                       
                         #include <iostream>                       
                         #include <cmath>                       
           
                         unsigned countBits(unsigned                                     int                                     number)                       
                         {                       
                                   
                                                 // log function in base 2                       
                                                 // take only integer part                       
                                                 return                                     (                                     int                                     )log2(number)+1;                       
                         }                       
           
                         // Driven program                       
                         int                                     main()                       
                         {                       
                                                 unsigned                                     int                                     num = 65;                       
                                                 std::cout<<countBits(num)<<                                     ''                                     ;                       
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by thedev05.                       

C

                         // C program to find total bit in given number                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         unsigned countBits(unsigned                                     int                                     number)                       
                         {                       
                                                 // log function in base 2                       
                                                 // take only integer part                       
                                                 return                                     (                                     int                                     )log2(number)+1;                       
                         }                       
           
                         // Driven program                       
                         int                                     main()                       
                         {                       
                                                 unsigned                                     int                                     num = 65;                       
                                                 printf                                     (                                     "%d"                                     , countBits(num));                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to                       
                         // find total bit                       
                         // in given number                       
                         import                                     java.io.*;                       
           
                         class                                     GFG                       
                         {                       
                                                 static                                     int                                     countBits(                                     int                                     number)                       
                                                 {                       
                                   
                                                 // log function in base 2                       
                                                 // take only integer part                       
                                                 return                                     (                                     int                                     )(Math.log(number) /                       
                                                 Math.log(                                     2                                     ) +                                     1                                     );                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main (String[] args)                       
                                                 {                       
                                                 int                                     num =                                     65                                     ;                       
                                   
                                                 System.out.println(countBits(num));                       
                                   
                                                 }                       
                         }                       
           
                         // This code is contributed by vij                       

Python3

                         # Python3 program to find                       
                         # total bit in given number                       
                         import                                     math                       
                         def                                     countBits(number):                       
                                   
                                                 # log function in base 2                       
                                                 # take only integer part                       
                                                 return                                     int                                     ((math.log(number)                                     /                       
                                                 math.log(                                     2                                     ))                                     +                                     1                                     );                       
           
                         # Driver Code                       
                         num                                     =                                     65                                     ;                       
                         print                                     (countBits(num));                       
           
                         # This code is contributed by mits                       

C#

                         // C# program to find total bit                       
                         // in given number                       
                         using                                     System;                       
           
                         class                                     GFG {                       
                                   
                                                 static                                     uint                                     countBits(                                     uint                                     number)                       
                                                 {                       
                                   
                                                 // log function in base 2                       
                                                 // take only integer part                       
                                                 return                                     (                                     uint                                     )Math.Log(number , 2.0) + 1;                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 uint                                     num = 65;                       
                                   
                                                 Console.WriteLine(countBits(num));                       
                                   
                                                 }                       
                         }                       
           
                         // This code is contributed by Sam007.                       

PHP

                         <?php                       
                         // PHP program to find total                       
                         // bit in given number                       
           
                         function                                     countBits(                                     $number                                     )                       
                         {                       
                                   
                                                 // log function in base 2                       
                                                 // take only integer part                       
                                                 return                                     (int)(log(                                     $number                                     ) /                       
                                                 log(2)) + 1;                       
                         }                       
           
                         // Driver Code                       
                         $num                                     = 65;                       
                         echo                                     (countBits(                                     $num                                     ));                       
           
                         // This code is contributed by Ajit.                       
                         ?>                       

Javascript

                         <script>                       
                         // JavaScript program to find total bit in given number                       
           
                                                 function                                     countBits(number) {                       
                                                 // log function in base 2                       
                                                 // take only integer part                       
                                                 return                                     Math.floor(Math.log2(number)+1);                       
                                                 }                       
                                   
                                                 // Driven program                       
           
                                                 let num = 65;                       
                                                 document.write(countBits(num));                       
                                   
                         // This code is contributed by Surbhi Tyagi                       
                         </script>                       

输出

方法2（使用位遍历）

C

                         /* Function to get no of bits in binary                       
                                                 representation of positive integer */                       
                         #include <stdio.h>                       
                                   
                         unsigned                                     int                                     countBits(unsigned                                     int                                     n)                       
                         {                       
                                                 unsigned                                     int                                     count = 0;                       
                                                 while                                     (n)                       
                                                 {                       
                                                 count++;                       
                                                 n >>= 1;                       
                                                 }                       
                                                 return                                     count;                       
                         }                       
                                   
                         /* Driver program*/                       
                         int                                     main()                       
                         {                       
                                                 int                                     i = 65;                       
                                                 printf                                     (                                     "%d"                                     , countBits(i));                       
                                                 return                                     0;                       
                         }                       

JAVA

                         /* Function to get no of bits in binary                       
                         representation of positive integer */                       
                         class                                     GFG {                       
           
                                                 static                                     int                                     countBits(                                     int                                     n)                       
                                                 {                       
                                                 int                                     count =                                     0                                     ;                       
                                                 while                                     (n !=                                     0                                     )                       
                                                 {                       
                                                 count++;                       
                                                 n >>=                                     1                                     ;                       
                                                 }                       
                                   
                                                 return                                     count;                       
                                                 }                       
                                   
                                                 /* Driver program*/                       
                                                 public                                     static                                     void                                     main(String[] arg)                       
                                                 {                       
                                                 int                                     i =                                     65                                     ;                       
                                                 System.out.print(countBits(i));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Smitha.                       

Python3

                         # Function to get no of bits                       
                         # in binary representation                       
                         # of positive integer                       
           
                         def                                     countBits(n):                       
           
                                                 count                                     =                                     0                       
                                                 while                                     (n):                       
                                                 count                                     +                                     =                                     1                       
                                                 n >>                                     =                                     1                       
                                   
                                                 return                                     count                       
           
                         # Driver program                       
                         i                                     =                                     65                       
                         print                                     (countBits(i))                       
           
                         # This code is contributed                       
                         # by Smitha                       

C#

                         /* Function to get no of bits                       
                         in binary representation of                       
                         positive integer */                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                                                 static                                     int                                     countBits(                                     int                                     n)                       
                                                 {                       
                                                 int                                     count = 0;                       
                                                 while                                     (n != 0)                       
                                                 {                       
                                                 count++;                       
                                                 n >>= 1;                       
                                                 }                       
                                   
                                                 return                                     count;                       
                                                 }                       
                                   
                                                 // Driver Code                       
                                                 static                                     public                                     void                                     Main ()                       
                                                 {                       
                                                 int                                     i = 65;                       
                                                 Console.Write(countBits(i));                       
                                                 }                       
                         }                       
           
                         // This code is contributed                       
                         // by akt_mit.                       

PHP

                         <?php                       
                         // PHP Code to get no of bits in binary                       
                         // representation of positive integer                       
           
                         // Function to get no of bits in binary                       
                         // representation of positive integer                       
                         function                                     countBits(                                     $n                                     )                       
                         {                       
                                                 $count                                     = 0;                       
                                                 while                                     (                                     $n                                     )                       
                                                 {                       
                                                 $count                                     ++;                       
                                                 $n                                     >>= 1;                       
                                                 }                       
                                                 return                                     $count                                     ;                       
                         }                       
           
                         // Driver Code                       
                         $i                                     = 65;                       
                         echo                                     (countBits(                                     $i                                     ));                       
           
                         // This code is contributed by Ajit.                       
                         ?>                       

Javascript

                         <script>                       
           
                         /* Function to get no of bits                       
                         in binary representation of                       
                         positive integer */                       
                         function                                     countBits(n)                       
                         {                       
                                                 var                                     count = 0;                       
                                                 while                                     (n != 0)                       
                                                 {                       
                                                 count++;                       
                                                 n >>= 1;                       
                                                 }                       
                                   
                                                 return                                     count;                       
                         }                       
           
                         // Driver Code                       
                         var                                     i = 65;                       
                         document.write(countBits(i));                       
           
                         </script>                       

输出

方法3（使用从二进制到字符串的转换）

Python3

                         # function to count the number of bits in a number n                       
                         def                                     count_bits(n):                       
                                                 # bin(n) returns a binary string representation of n preceded by '0b' in python                       
                                                 binary                                     =                                     bin                                     (n)                       
                                   
                                                 # we did -2 from length of binary string to ignore '0b'                       
                                                 return                                     len                                     (binary)                                     -                                     2                       
           
                         a                                     =                                     65                       
                         b                                     =                                     183                       
           
                         print                                     (f                                     "Total bits in {a}: {count_bits(a)}"                                     )                       
                         print                                     (f                                     "Total bits in {b}: {count_bits(b)}"                                     )                       
           
                         # This code is contributed by udit                       

输出

Total bits : 7Total bits : 8

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