Reverse Bits

Reverse bits of a given 32 bits unsigned integer.

For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as00111001011110000010100101000000).

unsigned int
reverse_bits(unsigned int value)
{
    unsigned int answer;
    unsigned int i;
    
    answer = 0;
    
    /*把一个unsigned int 数字1一直左移，直到它变成全0的时候，也就得到了该机器内unsigned int的长度*/
    for (i = 1; i != 0; i <<= 1)
    {
        answer <<= 1;
        if (value & 1) { answer |= 1; }
        value >>= 1;
    }
    
    return answer;
}