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我編寫了一個表示Date的C++類，並使用strptime/strftime來從字符串中編寫和實例化日期。使用strptime/strftime的結果不一致
當我使用的是bash的選項卡「樣本輸出」我的linux上運行了好幾次，有時我創建的同一日期和解析回來，有時我得到的最新一個的轉變小時（我的時區UTC + 1）。
所以，這裏發生了什麼，我不知道！
#ifndef DOLIPRANE_TIMEUNIT_HPP
#define DOLIPRANE_TIMEUNIT_HPP
enum TimeUnit {
DAY,
HOUR,
MINUTE,
SECOND
};
#endif
#ifndef DOLIPRANE_DATE_HPP
#define DOLIPRANE_DATE_HPP
#include <ctime>
#include <string>
class Date
{
public:
Date();
Date(time_t epoch);
/**
* Expected format: dd/MM/YYYY HH:mm:[ss]
*/
Date(const std::string &date);
~Date();
void
add(long val, TimeUnit u = SECOND);
bool
operator==(const Date &other) const;
bool
operator!=(const Date &other) const;
bool
operator<(const Date &other) const;
bool
operator<=(const Date &other) const;
bool
operator>(const Date &other) const;
bool
operator>=(const Date &other) const;
friend std::ostream&
operator<<(std::ostream &, const Date&);
friend std::istream&
operator>>(std::istream &, Date&);
private:
static const std::string FORMAT;
time_t m_time;
};
#endif
#include <iostream>
#include <stdexcept>
#include <ctime>
const char SEPARATOR=';';
const std::string Date::FORMAT="%d/%m/%Y %H:%M:%S";
Date::Date()
{
m_time = time(NULL);
}
Date::Date(time_t epoch)
: m_time(epoch)
{}
Date::Date(const std::string &date)
{
struct tm t;
const char* ptr = strptime(date.c_str(), FORMAT.c_str(), &t);
if (!ptr) {
std::string cause = "Cannot parse date ";
cause += date;
throw std::invalid_argument(cause);
}
m_time = mktime(&t);
if (m_time == -1) {
std::string cause = "Cannot compute epoch from " + date;
throw std::range_error(cause);
}
}
Date::~Date()
{
}
void
Date::add(long val, TimeUnit u) {
switch(u){
case DAY:
m_time += 86400*val;
break;
case HOUR:
m_time += 3600*val;
break;
case MINUTE:
m_time += 60*val;
break;
case SECOND:
m_time += val;
break;
default:
throw std::invalid_argument("Unknown TimeUnit specified");
}
}
bool
Date::operator==(const Date& o) const
{
return m_time == o.m_time;
}
bool
Date::operator!=(const Date& o) const
{
return ! (*this==o);
}
bool
Date::operator<(const Date &other) const
{
return m_time < other.m_time;
}
bool
Date::operator<=(const Date &other) const
{
return m_time <= other.m_time;
}
bool
Date::operator>(const Date &other) const
{
return m_time > other.m_time;
}
bool
Date::operator>=(const Date &other) const
{
return m_time >= other.m_time;
}
std::ostream&
operator<<(std::ostream& out, const Date &d)
{
struct tm* tm = localtime(&d.m_time);
char buffer[20];
strftime(buffer, 20, Date::FORMAT.c_str(), tm);
out << buffer << SEPARATOR;
return out;
}
std::istream&
operator>>(std::istream &in, Date &d)
{
std::string buf;
std::getline(in, buf, SEPARATOR);
Date o(buf);
d = o;
return in;
}
#include <iostream>
#include <fstream>
int
main(void)
{
Date d;
std::cout << d << std::endl;
std::ofstream out("tmp.txt");
out << d;
out.close();
std::ifstream in("tmp.txt");
Date d2;
in >> d2;
in.close();
std::cout << d2 << std::endl;
}
最後，怎麼我測試它：
$ for i in `seq 1 10`; do echo "test $i:"; ./test; rm tmp.txt; done
test 1:
26/03/2016 00:30:31;
26/03/2016 00:30:31;
test 2:
26/03/2016 00:30:31;
26/03/2016 00:30:31;
test 3:
26/03/2016 00:30:31;
25/03/2016 23:30:31;
test 4:
26/03/2016 00:30:31;
26/03/2016 00:30:31;
test 5:
26/03/2016 00:30:31;
25/03/2016 23:30:31;
test 6:
26/03/2016 00:30:31;
26/03/2016 00:30:31;
test 7:
26/03/2016 00:30:31;
25/03/2016 23:30:31;
test 8:
26/03/2016 00:30:31;
25/03/2016 23:30:31;
test 9:
26/03/2016 00:30:31;
25/03/2016 23:30:31;
test 10:
26/03/2016 00:30:31;
26/03/2016 00:30:31;
提供一個展示行爲並將其包含在此處的最小工作示例，不要鏈接到某處的代碼（一旦鏈接失效，問題就變得對其他人無用）。 – Borgleader
我無法在OS X上重現它。他說他在Ubuntu上運行，但我沒有得到什麼版本。 – xaxxon
我只是把鏈接中的所有選項卡放在一起（編譯它以確保它能正常工作），並用完整的代碼（你欠我remi）編輯問題 – xaxxon