利用比特操作知道你机器的字长

#include <stdio.h>
#include <stdlib.h>

int wordlength(void);

int main()
{
        printf("%d\n", wordlength());
        return 0;
}

int wordlength(void)
{
        int i;
        unsigned v = (unsigned) ~0; 
        for(i = 1; (v = v >> 1) > 0; i++)
                ;   
        return i;
}