c - 最初和 sleep 结束时在 C 中打印时间

Question

我正在尝试打印两次日期:

char *init_time = getTime();
// Do something and sleep 5 seconds
char *end = getTime();
printf("train 2 started at %s and arrived at %s\n", init_time, end);

获取时间:

char* getTime(){
    time_t result;
    result = time(NULL);
    return asctime(localtime(&result));
}

为什么打印的结果一样？

Answer 1

来自 asctime 手册页:

The asctime() function converts the broken-down time value tm into a null-terminated string with the same format as ctime(). The return value points to a statically allocated string which might be overwritten by subsequent calls to any of the date and time functions. The asctime_r() function does the same, but stores the string in a user-supplied buffer which should have room for at least 26 bytes.

换句话说，您对 asctime 的第二次调用将其结果存储在存储第一次调用结果的同一缓冲区中。

如果您想保留结果以备后用，请将结果复制到某处，或者在获得结果后立即打印，或者使用asctime_r。