unsigned long的一点应用

#include<stdio.h>
int main() {
    typedef unsigned long priority_type;

    static const priority_type LOWEST_PRIORITY = ~0UL;    //0为unsinged long类型，并且每位取反，下同。试下~，把%lu改为%ld再试下~
    static const priority_type LOW_PRIORITY = 1UL << 24;
    static const priority_type NORMAL_PRIORITY = 1UL << 16;
    static const priority_type HIGH_PRIORITY = 1UL << 8;
    static const priority_type HIGHEST_PRIORITY = 0;

    printf("LOWEST_PRIORITY=%lu, LOW_PRIORITY=%lu, NORMAL_PRIORITY=%lu, HIGH_PRIORITY=%lu, HIGHEST_PRIORITY=%lu\n",
            LOWEST_PRIORITY, LOW_PRIORITY, NORMAL_PRIORITY, HIGH_PRIORITY, HIGHEST_PRIORITY);
    return 0;
}