c++ - 使用“time.h”时崩溃

Question

==这条线下的最后一课==

这不是问题，我正在做我不完全理解std::ostringstream的坏事。"time.h"课后出现原始问题。最后的类如下所示：

时间戳.h

#ifndef __TIMESTAMP_H
#define __TIMESTAMP_H

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


class CTimestamp {

    private:
        std::string timestamp;
        time_t rawtime;
        struct tm errorTime;
        struct tm tempTime;
        bool quality;

    public:
        CTimestamp();
        void set(std::string inputTime);
        std::string get();
        std::string get(int modifiedBy);
        bool good();

        void getWeekday();  // Mainly for testing purposes - if this returns
                            // the correct weekday for your modified timestamp,
                            // you probably modified it correctly.
};

#endif

时间戳.cpp

#include "timestamp.h"
#include "time.h"
#include <string>
#include <stdlib.h>
#include <iostream>
#include <sstream>

CTimestamp::CTimestamp(){

    quality = 0;
}

void CTimestamp::set(std::string inputTime){

    quality = 1;

    int year, month, day, hour, minute, second;

    if (19 == inputTime.length()){

        inputTime.replace(10,1," ");
        inputTime.replace(13,1,":");
        inputTime.replace(16,1,":");

        year = atoi(inputTime.substr(0,4).c_str());
        month = atoi(inputTime.substr(5,2).c_str());
        day = atoi(inputTime.substr(8,2).c_str());
        hour = atoi(inputTime.substr(11,2).c_str());
        minute = atoi(inputTime.substr(14,2).c_str());         
        second = atoi(inputTime.substr(17,2).c_str());

        timestamp = inputTime;
    }
    else{
        quality = 0;
    }

    if(quality){
        // Get current time with the "time_t time(struct tm * timeptr)" function from time.h
        time(&rawtime);

        // Change to local time with "struct tm * localtime (const time_t * timer)" function from time.h
        errorTime = *localtime(&rawtime);

        // Change to the time of the timestamp
        errorTime.tm_year = year - 1900;   //Years since 1900
        errorTime.tm_mon  = month - 1;     //Months since january
        errorTime.tm_mday = day;           //Day of the month
        errorTime.tm_hour = hour;      //Hours since midnight
        errorTime.tm_min  = minute;        //minutes since hour
        errorTime.tm_sec  = second;        //Seconds since minute

        // modifies errorTime so overflows in lower units increment higher units then sets tm_wday and tm_yday
        mktime ( &errorTime );
    }
}

void CTimestamp::getWeekday(){

    const char * weekday[] = {"sun", "mon", "tue", "wed", "thu", "fri", "sat"};
    std::cout << weekday[errorTime.tm_wday];
}

std::string CTimestamp::get(){
    std::string returnValue = "Bad Initialization";
    if(quality){
        returnValue = timestamp;
    }
    return returnValue;
}

std::string CTimestamp::get(int modifiedBy){

    std::string returnValue = "Bad Initialization";
    if(quality){

        tempTime = errorTime;
        tempTime.tm_sec = (errorTime.tm_sec+modifiedBy);
        mktime( &tempTime);

        std::string year, month, day, hour, minute, second;

        // This compiler does not support the C++11 std::to_string but there is a workaround with stringstreams
        // http://www.cplusplus.com/articles/D9j2Nwbp/
        year   = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime.tm_year+1900)) )->str();
        month  = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime.tm_mon+1)) )->str();
        day    = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime.tm_mday)) )->str();
        hour   = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime.tm_hour)) )->str();
        minute = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime.tm_min)) )->str();
        second = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime.tm_sec)) )->str();

        if(month.length()  == 1) { month  = "0" + month;  }
        if(day.length()    == 1) { day    = "0" + day;    }
        if(hour.length()   == 1) { hour   = "0" + hour;   }
        if(minute.length() == 1) { minute = "0" + minute; }
        if(second.length() == 1) { second = "0" + second; }

        returnValue = year+"-"+month+"-"+day+" "+hour+":"+minute+":"+second;
    }

    return returnValue;
}

bool CTimestamp::good(){

    return quality;
}

==原始问题从这行开始==

我需要一些客户时间戳功能，我正在尝试为它创建一个类。不幸的是，当我尝试调用其中一个函数时，它会使我的程序崩溃，我不太确定为什么，特别是考虑到当我在一个较小的玩具程序中使用它来测试类时它不会崩溃。

#ifndef __TIMESTAMP_H
#define __TIMESTAMP_H

#include <string>
#include "time.h"
#include "debug.h"

class CTimestamp {

    private:
        std::string timestamp;
        time_t rawtime;
        struct tm * errorTime;
        struct tm * tempTime;
        bool quality;

    public:
        CTimestamp();
        void set(std::string inputTime);
        std::string get();
        std::string get(int modifiedBy);
        bool good();

        void getWeekday();  // Mainly for testing purposes - if this returns
                            // the correct weekday for your modified timestamp,
                            // you probably modified it correctly.
};

#endif

当我打电话时出现问题

std::cout << timeStamp.get(-30);

具体来说，此时：

year   = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_year+1900)) )->str();

这是以下方法的一部分：

std::string CTimestamp::get(int modifiedBy){
    if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

    std::string returnValue = "Bad Initialization";
    if(quality){

        tempTime->tm_year  = errorTime->tm_year;
        tempTime->tm_mon   = errorTime->tm_mon;
        tempTime->tm_mday  = errorTime->tm_mday;
        tempTime->tm_hour  = errorTime->tm_hour;
        tempTime->tm_min   = errorTime->tm_min;
        tempTime->tm_sec   = errorTime->tm_sec;
        mktime(tempTime);

        tempTime->tm_sec = tempTime->tm_sec + modifiedBy;
        mktime(tempTime);

        std::string year, month, day, hour, minute, second;

        if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

        // This compiler does not support the C++11 std::to_string but there is a workaround with stringstreams
        // http://www.cplusplus.com/articles/D9j2Nwbp/
        year   = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_year+1900)) )->str();
        month  = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_mon+1)) )->str();
        day    = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_mday)) )->str();
        hour   = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_hour)) )->str();
        minute = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_min)) )->str();
        second = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_sec)) )->str();

        if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

        if(month.length() == 1)
        {
            month = "0" + month;
        }
        if(day.length() == 1)
        {
            day = "0" + day;
        }
        if(hour.length() == 1)
        {
            hour = "0" + hour;
        }
        if(minute.length() == 1)
        {
            minute = "0" + minute;
        }
        if(second.length() == 1)
        {
            second = "0" + second;
        }

        if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

        returnValue = year+"-"+month+"-"+day+" "+hour+":"+minute+":"+second;

        if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

    }

    if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

    return returnValue;
}

编辑

好的，这让我很奇怪：

当我打电话

std::cout << timeStamp.get();

它在我指示的线上崩溃。

当我转而去

std::string hey = timeStamp.get();
std::cout << hey;

它在第二__DEBUG__条语句上崩溃（紧随其后if(quality)）

编辑编辑

errorTime 在这里初始化：

void CTimestamp::set(std::string inputTime){

    quality = 1;

    int year, month, day, hour, minute, second;

    if (19 == inputTime.length()){

        inputTime.replace(10,1," ");
        inputTime.replace(13,1,":");
        inputTime.replace(16,1,":");

        year = atoi(inputTime.substr(0,4).c_str());
        month = atoi(inputTime.substr(5,2).c_str());
        day = atoi(inputTime.substr(8,2).c_str());
        hour = atoi(inputTime.substr(11,2).c_str());
        minute = atoi(inputTime.substr(14,2).c_str());         
        second = atoi(inputTime.substr(17,2).c_str());

        timestamp = inputTime;
    }
    else{
        quality = 0;
    }

    if(quality){
        // Get current time with the "time_t time(struct tm * timeptr)" function from time.h
        time(&rawtime);

        // Change to local time
        errorTime = localtime(&rawtime);

        // Change to the time of the timestamp
        errorTime->tm_year = year - 1900;   //Years since 1900
        errorTime->tm_mon  = month - 1;     //Months since january
        errorTime->tm_mday = day;           //Day of the month
        errorTime->tm_hour = hour;          //Hours since midnight
        errorTime->tm_min  = minute;        //minutes since hour
        errorTime->tm_sec  = second;        //Seconds since minute

        // modifies errorTime so overflows in lower units increment higher units then sets tm_wday and tm_yday
        mktime ( errorTime );
    }
}

编辑编辑编辑

我试着摆脱花哨的指针工作，让它占用更多的行。不幸的是，它似乎不起作用：

    /*
    year   = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_year+1900)) )->str();
    month  = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_mon+1)) )->str();
    day    = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_mday)) )->str();
    hour   = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_hour)) )->str();
    minute = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_min)) )->str();
    second = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_sec)) )->str();
    */

    int timeConvertINT;
    std::ostringstream timeConvertOSS;

    timeConvertINT = (tempTime->tm_year)+1900;
    timeConvertOSS << timeConvertINT;
    year = timeConvertOSS.str();

    timeConvertINT = (tempTime->tm_mon)+1;
    timeConvertOSS << timeConvertINT;
    month = timeConvertOSS.str();

    timeConvertINT = (tempTime->tm_mday);
    timeConvertOSS << timeConvertINT;
    day = timeConvertOSS.str();

    timeConvertINT = (tempTime->tm_hour);
    timeConvertOSS << timeConvertINT;
    hour = timeConvertOSS.str();

    timeConvertINT = (tempTime->tm_min);
    timeConvertOSS << timeConvertINT;
    minute = timeConvertOSS.str();

    timeConvertINT = (tempTime->tm_sec);
    timeConvertOSS << timeConvertINT;
    second = timeConvertOSS.str();

编辑编辑编辑编辑

嗯。因此，ostreamstring 似乎不是这里的违规者 - 即使我将所有 OSS 功能注释掉并硬编码回复，它也会在该行崩溃。

这意味着在这个块中：

if(quality){

    if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

    tempTime->tm_year  = errorTime->tm_year;
    tempTime->tm_mon   = errorTime->tm_mon;
    tempTime->tm_mday  = errorTime->tm_mday;
    tempTime->tm_hour  = errorTime->tm_hour;
    tempTime->tm_min   = errorTime->tm_min;
    tempTime->tm_sec   = errorTime->tm_sec;
    mktime(tempTime);

    if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

    tempTime->tm_sec = tempTime->tm_sec + modifiedBy;
    mktime(tempTime);

    std::string year, month, day, hour, minute, second;

    if ( 1 < __DEBUG__ ){std::cout << "\nDEBUG " << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ ;}

    year = "2013";
    month = "11";
    day = "05";
    hour = "12";
    minute = "00";
    second = "00";

调用它时，我看到了第一个调试输出（以后没有）

std::string hey = timeStamp.get();
std::cout << hey;

但是当我称之为

std::cout << timeStamp.get();

之后我看到调试输出

std::string year, month, day, hour, minute, second;

score 3 · Accepted Answer

神秘的崩溃和指针一起出现，所以在取消引用它们之前检查tempTime并errorTime指向有效对象。发布的代码没有显示您初始化tempTime的位置，因此这是开始查找的位置。

除了为指针赋值之外，请确保在使用指针时对象的生命周期仍然有效。您不想保存指向超出范围的临时对象的指针。

score 2 · Accepted Answer

代码“似乎”合法，但形式上 - 它实际上格式错误，因为您正在获取临时地址。&(std::ostringstream() << (tempTime->tm_year+1900)).

你可以很容易地避免它——简单地写(std::ostringstream() << (tempTime->tm_year+1900)).str()。如果它仍然崩溃 - 尝试给 std::ostringstream() 一个名字，比如

std::ostringstream() oss;
oss << (tempTime->tm_year+1900);
oss.str();

如果它也没有帮助 - 我现在没有想法。

c++ - 使用“time.h”时崩溃

2 回答 2

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