直接上代码

#include <stdio.h>
#include <sys/time.h>
#include <string.h>
#include <time.h>
	
long long get_timestamp(void)//获取时间戳函数
{
    long long tmp;
    struct timeval tv;

    gettimeofday(&tv, NULL);
    tmp = tv.tv_sec;
    tmp = tmp * 1000;
    tmp = tmp + (tv.tv_usec / 1000);

    return tmp;
}

void get_format_time_string(char *str_time) //获取格式化时间
{
	time_t now;
    struct tm *tm_now;
    char datetime[128];
 
    time(&now);
    tm_now = localtime(&now);
    strftime(datetime, 128, "%Y-%m-%d %H:%M:%S", tm_now);
 
    printf("now datetime : %s\n", datetime);
	strcpy(str_time, datetime);
}

int main()
{
	char *format_time_string[128] = {0};
	long long curr_time = (long long)get_timestamp();
	get_format_time_string((char *)format_time_string);
	printf("timestamp:%lld, format time:%s",curr_time,format_time_string);
	return 0;
}

PS:localtime_s是线程安全的，优于localtime

时间戳转换成格式字符串

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

void get_format_time_st(time_t t, char *pcTime)
{
  struct tm *tm_t;
  tm_t = localtime(&t);
  strftime(pcTime,128,"%FT%T+0800",tm_t);
}

int main(void) { 
    unsigned long long curr_time = 1610617450;
    char time_str[256] = {0};
    time_t time = (time_t)curr_time;
    get_format_time_st(time, (char *)time_str);
	printf("%s",time_str);
	return 0;
}

结果输出：2021-01-14T09:44:10+0800

获取毫秒级时间格式

void get_format_time_ms(char *str_time) { 
    struct tm *tm_t;
    struct timeval time;
    
    gettimeofday(&time,NULL);
    tm_t = localtime(&time.tv_sec);
    if(NULL != tm_t) {
        sprintf(str_time,"%04d-%02d-%02d %02d:%02d:%02d.%03ld",
            tm_t->tm_year+1900,
            tm_t->tm_mon+1, 
            tm_t->tm_mday,
            tm_t->tm_hour, 
            tm_t->tm_min, 
            tm_t->tm_sec,
            time.tv_usec/1000);
    }
    
    return;
}

输出结果：2022-07-26 11:32:38.653

格式化时间转换成时间戳

long long format_time_to_timestamp() {
	struct tm timeinfo;
    time_t timestamp;

    // 设置时间信息 这里示例 2023/08/08 17:43:11
	timeinfo.tm_year = 2023 - 1900; // 年份需要减去1900
    timeinfo.tm_mon = 8 - 1; // 月份是从0开始的，所以需要减去1
    timeinfo.tm_mday = 8; // 日
    timeinfo.tm_hour = 17 - 8; // 时
    timeinfo.tm_min = 43; // 分
    timeinfo.tm_sec = 11; // 秒
    // 转换为时间戳
    timestamp = mktime(&timeinfo);
	printf("ts :%ld\n", timestamp);
	return timestamp;
}

输出结果：
ts :1691487791

在线时间戳转换网站验证