在没有模运算符的情况下检查数字是否为奇数或偶数-yiteyi-C++库

给定一个数字，检查它是偶数还是奇数。

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例如：

Input: n = 11Output: OddInput: n = 10Output: Even

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

方法1： 使用循环。我们的想法是从布尔标志变量true开始，并将其切换n次。如果flag变量返回原始值（这是真的），那么n是偶数。否则n是假的。

下面是这个想法的实施。

C++

                         // A simple C++ program to check for                       
                         // even or odd                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // Returns true if n is even, else odd                       
                         bool                                     isEven(                                     int                                     n)                       
                         {                       
                                                 bool                                     isEven =                                     true                                     ;                       
                                                 for                                     (                                     int                                     i=1;  i <= n; i++)                       
                                                 isEven = !isEven;                       
                                                 return                                     isEven;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 101;                       
                                                 isEven(n) ? cout <<                                     "Even"                                     : cout <<                                     "Odd"                                     ;                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // A simple Java program to                       
                         // check for even or odd                       
           
                         class                                     GFG {                       
                                   
                                                 // Returns true if n                       
                                                 // is even, else odd                       
                                                 static                                     boolean                                     isEven(                                     int                                     n)                       
                                                 {                       
                                                 boolean                                     isEven =                                     true                                     ;                       
                                   
                                                 for                                     (                                     int                                     i =                                     1                                     ; i <= n; i++)                       
                                                 isEven = !isEven;                       
                                   
                                                 return                                     isEven;                       
                                                 }                       
                                   
                                   
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                   
                                                 int                                     n =                                     101                                     ;                       
                                                 if                                     (isEven(n))                       
                                                 System.out.println(                                     "Even"                                     );                       
                                                 else                       
                                                 System.out.println(                                     "Odd"                                     );                       
                                   
                                                 }                       
                         }                       
           
                         // This code is contributed by Sam007                       

Python3

                         # A simple Python program to                       
                         # check for even or odd                       
           
                         # Returns true if n is even,                       
                         # else odd                       
                         def                                     isEven(n):                       
                                                 isEven                                     =                                     True                                     ;                       
                                                 for                                     i                                     in                                     range                                     (                                     1                                     , n                                     +                                     1                                     ):                       
                                                 if                                     isEven                                     =                                     =                                     True                                     :                       
                                                 isEven                                     =                                     False                                     ;                       
                                                 else                                     :                       
                                                 isEven                                     =                                     True                                     ;                       
           
                                                 return                                     isEven;                       
           
                         # Driver code                       
                         n                                     =                                     101                                     ;                       
                         if                                     isEven(n)                                     =                                     =                                     True                                     :                       
                                                 print                                     (                                     "Even"                                     );                       
                         else                                     :                       
                                                 print                                     (                                     "Odd"                                     );                       
                                   
                         # This code is contributed by                       
                         # Manish Shaw (manishshaw1)                       

C#

                         // A simple C# program to check for                       
                         // even or odd                       
                         using                                     System;                       
           
                         public                                     class                                     GFG {                       
                                   
                                                 // Returns true if n is even,                       
                                                 // else odd                       
                                                 static                                     bool                                     isEven(                                     int                                     n)                       
                                                 {                       
                                                 bool                                     isEven =                                     true                                     ;                       
                                   
                                                 for                                     (                                     int                                     i = 1; i <= n; i++)                       
                                                 isEven = !isEven;                       
                                   
                                                 return                                     isEven;                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     n = 101;                       
                                                 if                                     (isEven(n))                       
                                                 Console.Write(                                     "Even"                                     );                       
                                                 else                       
                                                 Console.Write(                                     "Odd"                                     );                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Sam007.                       

PHP

                         <?php                       
                         // A simple PHP program to check for                       
                         // even or odd                       
           
                         // Returns true if n is even,                       
                         // else odd                       
                         function                                     isEven(                                     $n                                     )                       
                         {                       
                                                 $isEven                                     = true;                       
                                                 for                                     (                                     $i                                     = 1;                                     $i                                     <=                                     $n                                     ;                                     $i                                     ++)                       
                                                 $isEven                                     = !                                     $isEven                                     ;                       
                                                 return                                     $isEven                                     ;                       
                         }                       
           
                                                 // Driver code                       
                                                 $n                                     = 101;                       
                                                 $is                                     =isEven(                                     $n                                     ) ?                                     "Even"                                     :                                     "Odd"                                     ;                       
                                                 echo                                     "$is"                       
           
                         // This code is contributed by ajit                       
                         ?>                       

Javascript

                         <script>                       
           
                         // A simple Javascript program to check                       
                         // for even or odd                       
           
                         // Returns true if n is even,                       
                         // else odd                       
                         function                                     isEven(n)                       
                         {                       
                                                 let isEven =                                     true                                     ;                       
                                   
                                                 for                                     (let i = 1; i <= n; i++)                       
                                                 isEven = !isEven;                       
                                   
                                                 return                                     isEven;                       
                         }                       
           
                         // Driver code                       
                         let n = 101;                       
                         if                                     (isEven(n))                       
                                                 document.write(                                     "Even"                                     );                       
                         else                       
                                                 document.write(                                     "Odd"                                     );                       
                                   
                         // This code is contributed by mukesh07                       
           
                         </script>                       

输出：

Odd

方法2： 乘和除2。将数字除以2，再乘以2，如果结果与输入相同，则为偶数，否则为奇数。

C++

                         // A simple C++ program to check for                       
                         // even or odd                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // Returns true if n is even, else odd                       
                         bool                                     isEven(                                     int                                     n)                       
                         {                       
                                                 // Return true if n/2 does not result                       
                                                 // in a float value.                       
                                                 return                                     ((n / 2) * 2 == n);                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 101;                       
                                                 isEven(n) ? cout <<                                     "Even"                                     : cout <<                                     "Odd"                                     ;                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // A simple Java program                       
                         // to check for even or odd                       
           
                         class                                     GFG {                       
                                   
                         // Returns true if n                       
                         // is even, else odd                       
                         static                                     boolean                                     isEven(                                     int                                     n)                       
                         {                       
                                   
                                                 // Return true if                       
                                                 // n/2 does not result                       
                                                 // in a float value.                       
                                                 return                                     ((n /                                     2                                     ) *                                     2                                     == n);                       
                         }                       
           
                         // Driver code                       
                         public                                     static                                     void                                     main(String[] args)                       
                         {                       
                                                 int                                     n =                                     101                                     ;                       
                                                 if                                     (isEven(n) !=                                     false                                     )                       
                                                 System.out.print(                                     "Even"                                     );                       
                                                 else                       
                                                 System.out.print(                                     "Odd"                                     );                       
                         }                       
                         }                       
           
                         // This code is contributed by                       
                         // Smitha Dinesh Semwal.                       

Python3

                         # A simple Python 3 program                       
                         # to check for even or odd                       
           
                         # Returns true if n                       
                         # is even, else odd                       
                         def                                     isEven(n):                       
           
                                   
                                                 # Return true if                       
                                                 # n/2 does not result                       
                                                 # in a float value.                       
                                                 return                                     (                                     int                                     (n                                     /                                     2                                     )                                     *                                     2                                     =                                     =                                     n)                       
           
           
                         # Driver code                       
                         n                                     =                                     101                       
                         if                                     (isEven(n) !                                     =                                     False                                     ):                       
                                                 print                                     (                                     "Even"                                     )                       
                         else                                     :                       
                                                 print                                     (                                     "Odd"                                     )                       
           
                         # This code is contributed by                       
                         # Smitha Dinesh Semwal.                       

C#

                         // A simple C# program                       
                         // to check for even or odd                       
                         using                                     System;                       
                         class                                     GFG {                       
                                   
                         // Returns true if n                       
                         // is even, else odd                       
                         static                                     bool                                     isEven(                                     int                                     n)                       
                         {                       
                                   
                                                 // Return true if                       
                                                 // n/2 does not result                       
                                                 // in a float value.                       
                                                 return                                     ((n / 2) * 2 == n);                       
                         }                       
           
                         // Driver code                       
                         public                                     static                                     void                                     Main(String[] args)                       
                         {                       
                                                 int                                     n = 101;                       
                                                 if                                     (isEven(n) !=                                     false                                     )                       
                                                 Console.Write(                                     "Even"                                     );                       
                                                 else                       
                                                 Console.Write(                                     "Odd"                                     );                       
                         }                       
                         }                       
           
                         // This code is contributed by                       
                         // Smitha Dinesh Semwal.                       

PHP

                         <?php                       
                         // A simple PHP program to                       
                         // check for even or odd                       
           
                         // Returns true if n                       
                         // is even, else odd                       
                         function                                     isEven(                                     $n                                     )                       
                         {                       
                                                 // Return true if n/2                       
                                                 // does not result                       
                                                 // in a float value.                       
                                                 return                                     ((int)(                                     $n                                     / 2) * 2 ==                                     $n                                     );                       
                         }                       
           
                         // Driver code                       
                         $n                                     = 101;                       
                         if                                     (isEven(                                     $n                                     ))                       
                                                 echo                                     (                                     "Even"                                     );                       
                         else                       
                                                 echo                                     (                                     "Odd"                                     );                       
                                   
                         // This code is contributed by                       
                         // Manish Shaw (manishshaw1)                       
                         ?>                       

Javascript

                         <script>                       
           
                         // A simple Javascript program to                       
                         // check for even or odd                       
           
                         // Returns true if n is even,                       
                         // else odd                       
                         function                                     isEven(n)                       
                         {                       
                                   
                                                 // Return true if n/2 does not result                       
                                                 // in a float value.                       
                                                 return                                     (parseInt(n / 2, 10) * 2 == n);                       
                         }                       
           
                         // Driver code                       
                         let n = 101;                       
                         isEven(n) ? document.write(                                     "Even"                                     ) :                       
                                                 document.write(                                     "Odd"                                     );                       
                                   
                         // This code is contributed by divyeshrabadiya07                       
           
                         </script>                       

输出：

Odd

方法3： 使用位运算符&。 A. 更好的解决方案 就是使用位运算符。我们需要检查最后一位是否为1。如果最后一位是1，那么这个数字是奇数，否则总是偶数。

说明：

 input : 5    // odd   00000101               & 00000001                --------------                   00000001       --------------input : 8     //even   00001000               & 00000001                 --------------                  00000000        --------------

下面是这个想法的实施。

C++

                         // A simple C++ program to check for                       
                         // even or odd                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // Returns true if n is even, else odd                       
                         bool                                     isEven(                                     int                                     n)                       
                         {                       
                                                 // n&1 is 1, then odd, else even                       
                                                 return                                     (!(n & 1));                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 101;                       
                                                 isEven(n) ? cout <<                                     "Even"                                     : cout <<                                     "Odd"                                     ;                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // A simple Java program to check for                       
                         // even or odd                       
                         import                                     java.io.*;                       
                         import                                     java.util.*;                       
           
                         public                                     class                                     GFG {                       
                                   
                                                 // Returns 0 if n                       
                                                 // is even, else odd                       
                                                 static                                     int                                     isEven(                                     int                                     n)                       
                                                 {                       
                                   
                                                 // n&1 is 1, then                       
                                                 // odd, else even                       
                                                 return                                     (n &                                     1                                     );                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 int                                     n =                                     101                                     ;                       
                                                 if                                     (isEven(n)==                                     0                                     )                       
                                                 System.out.print(                                     "Even"                                     );                       
                                                 else                       
                                                 System.out.print(                                     "Odd"                                     );                       
                                                 }                       
                         }                       
                                   
                         // This code is contributed                       
                         // by Manish Shaw (manishshaw1)                       

Python3

                         # A simple Python program to                       
                         # check for even or odd                       
                         # Returns 0 if n                       
                         # is even, else odd                       
                         def                                     isEven(n) :                       
                                   
                                                 # n&1 is 1, then                       
                                                 # odd, else even                       
                                                 return                                     (n &                                     1                                     );                       
                                   
                         # Driver code                       
                         n                                     =                                     101                                     ;                       
                         if                                     (isEven(n)                                     =                                     =                                     0                                     ) :                       
                                                 print                                     (                                     "Even"                                     );                       
                         else                                     :                       
                                                 print                                     (                                     "Odd"                                     );                       
                                   
                         # This code is contributed                       
                         # by Manish Shaw (manishshaw1)                       

C#

                         // A simple C# program to check for                       
                         // even or odd                       
                         using                                     System;                       
                         using                                     System.Collections.Generic;                       
           
                         class                                     GFG {                       
                                   
                                                 // Returns 0 if n                       
                                                 // is even, else odd                       
                                                 static                                     int                                     isEven(                                     int                                     n)                       
                                                 {                       
                                   
                                                 // n&1 is 1, then                       
                                                 // odd, else even                       
                                                 return                                     (n & 1);                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     n = 101;                       
                                                 if                                     (isEven(n)==0)                       
                                                 Console.Write(                                     "Even"                                     );                       
                                                 else                       
                                                 Console.Write(                                     "Odd"                                     );                       
                                                 }                       
                         }                       
           
                         // This code is contributed                       
                         // by Manish Shaw (manishshaw1)                       

PHP

                         <?php                       
                         // A simple PHP program to                       
                         // check for even or odd                       
                         // Returns 0 if n                       
                         // is even, else odd                       
                         function                                     isEven(                                     $n                                     )                       
                         {                       
                                   
                                                 // n&1 is 1, then                       
                                                 // odd, else even                       
                                                 return                                     (                                     $n                                     & 1);                       
                         }                       
           
                         // Driver code                       
                         $n                                     = 101;                       
                         if                                     (isEven(                                     $n                                     ) == 0)                       
                                                 echo                                     (                                     "Even"                                     );                       
                         else                       
                                                 echo                                     (                                     "Odd"                                     );                       
                                   
                         // This code is contributed                       
                         // by Manish Shaw (manishshaw1)                       
                         ?>                       

Javascript

                         <script>                       
                                                 // A simple Javascript program to check for even or odd                       
                                   
                                                 // Returns true if n is even, else odd                       
                                                 function                                     isEven(n)                       
                                                 {                       
                                                 // n&1 is 1, then odd, else even                       
                                                 return                                     (!(n & 1));                       
                                                 }                       
                                   
                                                 let n = 101;                       
                                                 isEven(n) ? document.write(                                     "Even"                                     ) : document.write(                                     "Odd"                                     );                       
           
                         </script>                       

输出：

Odd

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