绘声绘彩的生活志

 
#include <stdio.h>   
#pragma pack( push, 1 )
union type
{
    unsigned char udpdatatype;
    struct {
        unsigned int version:4;
        unsigned int reserved_sign:2;
        unsigned int needack_sign:1;
        unsigned int resend_sign :1;
    } protocol;
};
 
#pragma pack( pop )
 
int main(int argc, const char *argv[])
{
    printf("sizeof: %u.\n", sizeof(union type));
    return 0;
}

#include 
#include 
 
int main(int argc, const char *argv[])
{
    time_t t;
    struct tm m;
    char resultbuf[8];
    int resultbuflen = sizeof(resultbuf);
    int len;
    t = time(NULL);
    localtime_r(&t, &m);
    len = strftime(resultbuf, resultbuflen, "%Y%m%d", &m);
    if(len<resultbuflen)
        printf("something wrong, result len:%d.\n\t%s.\n", len, resultbuf);
    else
        printf("now: %s.\n", resultbuf);
    return 0;
}