Write a C program to find the parity of an unsigned integer

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本文提供了一种高效的C语言程序，用于判断无符号整数的奇偶性，通过位操作实现。程序核心在于使用循环迭代，通过逐次清除最低位的1来确定数字的奇偶性。

reference:

http://www.geeksforgeeks.org/write-a-c-program-to-find-the-parity-of-an-unsigned-integer/

Problem Definition:

Parity: Parity of a number refers to whether it contains an odd or even number of 1-bits. The number has “odd parity”, if it contains odd number of 1-bits and is “even parity” if it contains even number of 1-bits.

Solution:

1. Initialize parity = 0
2. Loop while n != 0      
      a. Invert parity 
             parity = !parity
      b. Unset rightmost set bit
             n = n & (n-1)
3. return parity

Code:

/* Function to get parity of number n. It returns 1
   if n has odd parity, and returns 0 if n has even
   parity */
bool getParity(unsigned int n)
{
    bool parity = 0;
    while (n)
    {
        parity = !parity;
        n      = n & (n - 1);
    }        
    return parity;
}