使用struct tm打印特定日期和strftime

Question

所以我需要专门使用struct tm来打印我的生日,我成功了.但是,我还需要使用strftime()以不同的格式打印它.这就是我遇到问题的地方,因为strftime()只识别指针参数.

#include <stdio.h>
#include <time.h>

int main(){

    struct tm str_bday;
    time_t time_bday;
    char buffer[15];

    str_bday.tm_year = 1994 - 1900 ;
    str_bday.tm_mon = 7 - 1;
    str_bday.tm_mday = 30;
    str_bday.tm_hour = 12;
    str_bday.tm_min = 53;
    time_bday = mktime(&str_bday);
    if(time_bday == (time_t)-1)
        fprintf(stdout,"error\n");
    else
        {
        fprintf(stdout,"My birthday in second is: %ld \n",time_bday);
        fprintf(stdout,"My birthday is: %s\n", ctime(&time_bday));//Wed July 22 12:53:00 1998
        strftime(buffer,15,"%d/%m/%Y",time_bday);
        fprintf(stdout,"My birthday in D/M/Y format is %s",buffer);
        }
    return 0;
}

错误是:

Error:  passing argument 4 of ‘strftime’ makes pointer from integer without a cast

    expected ‘const struct tm * restrict’ but argument is of type ‘time_t’

有人可以告诉我如何解决它？

编辑:将time_bday更改为&str_bday有效!但现在程序每次运行时都会输出随机时间和日期.

编辑:而不是strftime()之后的fprintf(),我使用了puts(缓冲区),它运行得很好.此外,将缓冲区[15]更改为缓冲区[30],因为我有小时,分钟和秒.

Answer 1

通过查看strftime原型,你可以看到你应该传递一个const struct tm*最后一个参数:

size_t strftime(char *s, size_t maxsize, const char *format, const struct tm *timeptr);

这将&str_bday取代time_bday你的情况.

struct tm有几个字段你没有初始化,因此采取不确定的值,导致你看到的时间跳跃.struct tm str_bday = {0}在插入值之前,可以使用,将所有字段初始化为零.