C++学习之路： 时间戳 封装成类

#ifndef TIMESTAMP_H
#define TIMESTAMP_H 

#include <string>
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif /* __STDC_FORMAT_MACROS */
#include <inttypes.h>

class Timestamp
{
public:
    Timestamp();
    Timestamp(int64_t value);

    bool isValid() const
    { return value_ > 0; }

    std::string toString() const;
    std::string toFormatString() const;  

    static Timestamp now();           //获取时间戳

private:
    int64_t value_; //微秒级别的时间戳
};


#endif  /*TIMESTAMP_H*/

源文件

#include "Timestamp.h"
#include <time.h>
#include <sys/time.h>
#include <stdio.h>
#include <string.h>
using namespace std;


Timestamp::Timestamp()
    :value_(0)
{

}

Timestamp::Timestamp(int64_t value)
    :value_(value)
{

}

string Timestamp::toString() const
{
    //1411373695.488096
    int64_t sec = value_ / (1000 * 1000);
    int64_t usec = value_ % (1000 * 1000);
    // %06lld
    char text[32] = {0};
    snprintf(text, sizeof text, "%lld.%06lld", sec, usec);

    return string(text);
}

string Timestamp::toFormatString() const
{
    //20140922 08:14:55.488096
    time_t sec = value_ / (1000 * 1000);
    int64_t usec = value_ % (1000 * 1000);
    struct tm st;
    //gmtime_r(&sec, &st);
    localtime_r(&sec, &st);         //localtime只是把时间戳转换为我们所熟知的 2014.7.40 xx：xx：xx 的格式 并不获取时间

    char text[100] = {0};
    snprintf(text, sizeof text, "%04d%02d%02d %02d:%02d:%02d.%06lld", st.tm_year + 1900, st.tm_mon + 1, st.tm_mday, st.tm_hour, st.tm_min
        , st.tm_sec, usec);
    return string(text);
}

Timestamp Timestamp::now()
{
    struct timeval tv;
    memset(&tv, 0, sizeof tv);
    gettimeofday(&tv, NULL);           //获取时间戳偏移量  核心函数，获取1970.1.1 00:00:00 到现在经过的秒数，精确到毫秒级

    int64_t val = 0;
    val += static_cast<int64_t>(tv.tv_sec) * 1000 * 1000;
    val += tv.tv_usec;

    return Timestamp(val);
}

测试文件

#include "Timestamp.h"
#include <iostream>
using namespace std;

int main(int argc, char const *argv[])
{
    Timestamp now = Timestamp::now();

    cout << now.toString() << endl;
    cout << now.toFormatString() << endl;
    return 0;
}