检查是否设置了第K位-yiteyi-C++库

给定一个数字n，检查是否设置了n的第k位。

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例如：

Input : n = 5, k = 1Output : SET5 is represented as 101 in binary and has its first bit set.Input : n = 2, k = 3Output : NOT SET2 is represented as 10 in binary, all higher i.e. beyond MSB, bits are NOT SET.

建议：请在“上解决” 实践 “首先，在讨论解决方案之前。

方法1（使用左移位运算符） 以下是查找第k位值的简单步骤：

1) Left shift given number 1 by k-1 to create a number that has only set bit as k-th bit.   temp = 1 << (k-1)2) If bitwise AND of n and temp is non-zero, then result is SET else result is NOT SET.

例子：

 n = 75 and k = 4 temp = 1 << (k-1) = 1 << 3 = 8  Binary Representation of temp = 0..00001000  Binary Representation of n = 0..01001011  Since bitwise AND of n and temp is non-zero, result is SET.

C++

                         // CPP program to check if k-th bit                       
                         // of a given number is set or not                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         void                                     isKthBitSet(                                     int                                     n,                                     int                                     k)                       
                         {                       
                                                 if                                     (n & (1 << (k - 1)))                       
                                                 cout <<                                     "SET"                                     ;                       
                                                 else                       
                                                 cout <<                                     "NOT SET"                                     ;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 5, k = 1;                       
                                                 isKthBitSet(n, k);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to check if k-th bit                       
                         // of a given number is set or not                       
           
                         class                                     Number {                       
                                                 public                                     static                                     void                                     isKthBitSet(                                     int                                     n,                       
                                                 int                                     k)                       
                                                 {                       
                                                 if                                     ((n & (                                     1                                     << (k -                                     1                                     ))) >                                     0                                     )                       
                                                 System.out.print(                                     "SET"                                     );                       
                                                 else                       
                                                 System.out.print(                                     "NOT SET"                                     );                       
                                                 }                       
           
                                                 // driver code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 int                                     n =                                     5                                     , k =                                     1                                     ;                       
                                                 isKthBitSet(n, k);                       
                                                 }                       
                         }                       
           
                         // This code is contributed by rishabh_jain                       

Python3

                         # Python3 code to check if k-th bit                       
                         # of a given number is set or not                       
           
                         def                                     isKthBitSet(n, k):                       
                                                 if                                     n & (                                     1                                     << (k                                     -                                     1                                     )):                       
                                                 print                                     (                                     "SET"                                     )                       
                                                 else                                     :                       
                                                 print                                     (                                     "NOT SET"                                     )                       
           
                         # Driver code                       
                         n                                     =                                     5                       
                         k                                     =                                     1                       
                         isKthBitSet(n, k)                       
           
                         # This code is contributed by "Sharad_Bhardwaj".                       

C#

                         // C# program to check if k-th bit                       
                         // of a given number is set or not.                       
                         using                                     System;                       
           
                         class                                     GFG {                       
           
                                                 public                                     static                                     void                                     isKthBitSet(                                     int                                     n,                       
                                                 int                                     k)                       
                                                 {                       
                                                 if                                     ((n & (1 << (k - 1))) > 0)                       
                                                 Console.Write(                                     "SET"                                     );                       
                                                 else                       
                                                 Console.Write(                                     "NOT SET"                                     );                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     n = 5, k = 1;                       
           
                                                 isKthBitSet(n, k);                       
                                                 }                       
                         }                       
           
                         // This code is contributed by nitin mittal.                       

PHP

                         <?php                       
                         // PHP program to check if                       
                         // k-th bit of a given                       
                         // number is set or not                       
                         function                                     isKthBitSet(                                     $n                                     ,                                     $k                                     )                       
                         {                       
                                                 if                                     (                                     $n                                     & (1 << (                                     $k                                     - 1)))                       
                                                 echo                                     "SET"                                     ;                       
                                                 else                       
                                                 echo                                     "NOT SET"                                     ;                       
                         }                       
           
                         // Driver code                       
                         $n                                     = 5;                                     $k                                     = 1;                       
                         isKthBitSet(                                     $n                                     ,                                     $k                                     );                       
           
                         // This code is contributed                       
                         // by akt_mit                       
                         ?>                       

Javascript

                         <script>                       
                                                 // Javascript program to check if k-th bit                       
                                                 // of a given number is set or not.                       
                                   
                                                 function                                     isKthBitSet(n, k)                       
                                                 {                       
                                                 if                                     ((n & (1 << (k - 1))) > 0)                       
                                                 document.write(                                     "SET"                                     );                       
                                                 else                       
                                                 document.write(                                     "NOT SET"                                     );                       
                                                 }                       
                                   
                                                 let n = 5, k = 1;                       
                                   
                                                 isKthBitSet(n, k);                       
                                   
                         </script>                       

输出：

SET

方法2（使用右移运算符） 如果将n右移k-1，如果第k位设为0，则最后一位为1。

C++

                         // CPP program to check if k-th bit                       
                         // of a given number is set or not using                       
                         // right shift operator.                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         void                                     isKthBitSet(                                     int                                     n,                                     int                                     k)                       
                         {                       
                                                 if                                     ((n >> (k - 1)) & 1)                       
                                                 cout <<                                     "SET"                                     ;                       
                                                 else                       
                                                 cout <<                                     "NOT SET"                                     ;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 5, k = 1;                       
                                                 isKthBitSet(n, k);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to check if                       
                         // k-th bit of a given number                       
                         // is set or not using right                       
                         // shift operator.                       
                         import                                     java.io.*;                       
           
                         class                                     GFG                       
                         {                       
                         static                                     void                                     isKthBitSet(                                     int                                     n,                       
                                                 int                                     k)                       
                         {                       
                                                 if                                     (((n >> (k -                                     1                                     )) &                       
                                                 1                                     ) >                                     0                                     )                       
                                                 System.out.println(                                     "SET"                                     );                       
                                                 else                       
                                                 System.out.println(                                     "NOT SET"                                     );                       
                         }                       
           
                         // Driver code                       
                         public                                     static                                     void                                     main (String[] args)                       
                         {                       
                                                 int                                     n =                                     5                                     , k =                                     1                                     ;                       
                                                 isKthBitSet(n, k);                       
                         }                       
                         }                       
           
                         // This code is contributed                       
                         // by ajit                       

Python3

                         # PHP program to check if k-th bit of                       
                         # a given number is set or not using                       
                         # right shift operator.                       
           
                         def                                     isKthBitSet(n, k):                       
                                                 if                                     ((n >> (k                                     -                                     1                                     ))                                     and                                     1                                     ):                       
                                                 print                                     (                                     "SET"                                     )                       
                                                 else                                     :                       
                                                 print                                     (                                     "NOT SET"                                     )                       
           
                         # Driver code                       
                         n, k                                     =                                     5                                     ,                                     1                       
                         isKthBitSet(n, k)                       
           
                         # This code contributed by                       
                         # PrinciRaj1992                       

C#

                         // C# program to check if                       
                         // k-th bit of a given number                       
                         // is set or not using right                       
                         // shift operator                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                         static                                     void                                     isKthBitSet(                                     int                                     n,                       
                                                 int                                     k)                       
                         {                       
                                                 if                                     (((n >> (k - 1)) &                       
                                                 1) > 0)                       
                                                 Console.WriteLine(                                     "SET"                                     );                       
                                                 else                       
                                                 Console.WriteLine(                                     "NOT SET"                                     );                       
                         }                       
           
                         // Driver code                       
                         static                                     public                                     void                                     Main ()                       
                         {                       
                                                 int                                     n = 5, k = 1;                       
                                                 isKthBitSet(n, k);                       
                         }                       
                         }                       
           
                         // This code is contributed                       
                         // by ajit                       

PHP

                         <?php                       
                         // PHP program to check                       
                         // if k-th bit of a given                       
                         // number is set or not                       
                         // using right shift operator.                       
           
                         function                                     isKthBitSet(                                     $n                                     ,                                     $k                                     )                       
                         {                       
                                                 if                                     ((                                     $n                                     >> (                                     $k                                     - 1)) & 1)                       
                                                 echo                                     "SET"                                     ;                       
                                                 else                       
                                                 echo                                     "NOT SET"                                     ;                       
                         }                       
           
                         // Driver code                       
                         $n                                     = 5;                                     $k                                     = 1;                       
                         isKthBitSet(                                     $n                                     ,                                     $k                                     );                       
           
                         // This code is contributed                       
                         // by akt_mit                       
                         ?>                       

Javascript

                         <script>                       
           
                         // Javascript program to check if                       
                         // k-th bit of a given number                       
                         // is set or not using right                       
                         // shift operator.                       
           
                         function                                     isKthBitSet(n, k)                       
                         {                       
                                                 if                                     (((n >> (k - 1)) &                       
                                                 1) > 0)                       
                                                 document.write(                                     "SET"                                     );                       
                                                 else                       
                                                 document.write(                                     "NOT SET"                                     );                       
                         }                       
           
                         // Driver Code                       
           
                                                 let n = 5, k = 1;                       
                                                 isKthBitSet(n, k);                       
           
                         // This code is contributed by sanjoy_62.                       
                         </script>                       

输出：

SET

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