[数据结构与算法]写一个获取系统当前时间的类

头文件

#ifndef _TIMESTAMP_H_
#define _TIMESTAMP_H_

#include <iostream>
#include <string>

class Timestamp {
public:
    Timestamp();                                             // 默认构造
    explicit Timestamp(int64_t microSecondsSinceEpoch_);     // 有参构造
    static Timestamp now();                                  // 获取当前时间
    std::string toString() const;                            // toString方法


private:
    int64_t microSecondsSinceEpoch_;                         // 数据
};

#endif

源文件

#include "Timestamp.h"
#include <time.h>

// 默认构造 
Timestamp::Timestamp():microSecondsSinceEpoch_(0){}
// 有参构造
Timestamp::Timestamp(int64_t microSecondsSinceEpoch_):microSecondsSinceEpoch_(microSecondsSinceEpoch_){}
// 获取当前时间
Timestamp Timestamp::now()
{
    return Timestamp(time(NULL));        // 获取当前时间
}
// toString方法
std::string Timestamp::toString() const
{
    char buf[128] = {0};
    tm* tm_time = localtime(&microSecondsSinceEpoch_);       // 获取当前时间
    // 拼接年/月/日 时:分:秒
    snprintf(buf, 128, "%4d/%02d/%2d %02d:%02d:%02d",
        tm_time->tm_year + 1900,
        tm_time->tm_mon + 1,
        tm_time->tm_mday,
        tm_time->tm_hour,
        tm_time->tm_min,
        tm_time->tm_sec);
    return buf;
}

测试

// 测试一下
#include <iostream>
#include "Time.h"
int main(int argc, char** argv) {
    std::cout << Timestamp::now().toString() << std::endl;

    return 0;
}

?这里用到了tm这个类，查看源码

#ifndef __struct_tm_defined
#define __struct_tm_defined 1

#include <bits/types.h>

/* ISO C `broken-down time' structure.  */
struct tm
{
  int tm_sec;			/* Seconds.	[0-60] (1 leap second) */
  int tm_min;			/* Minutes.	[0-59] */
  int tm_hour;			/* Hours.	[0-23] */
  int tm_mday;			/* Day.		[1-31] */
  int tm_mon;			/* Month.	[0-11] */
  int tm_year;			/* Year	- 1900.  */
  int tm_wday;			/* Day of week.	[0-6] */
  int tm_yday;			/* Days in year.[0-365]	*/
  int tm_isdst;			/* DST.		[-1/0/1]*/

# ifdef	__USE_MISC
  long int tm_gmtoff;		/* Seconds east of UTC.  */
  const char *tm_zone;		/* Timezone abbreviation.  */
# else
  long int __tm_gmtoff;		/* Seconds east of UTC.  */
  const char *__tm_zone;	/* Timezone abbreviation.  */
# endif
};

#endif

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