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社区首页 >问答首页 >使用"time.h“时崩溃

问使用"time.h“时崩溃
EN

Stack Overflow用户
提问于 2013-12-17 13:26:36
回答 2查看 833关注 0票数 2

==FINAL类在LINE==下面

这不是std::ostringstream的问题，我用"time.h"做坏事，但我没有完全理解。原来的问题出现在课后。最后一节课如下所示：

时间戳p.h

代码语言：javascript
复制
#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

timestamp.cpp

代码语言：javascript
复制
#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;
}

==ORIGINAL问题从LINE==下面开始

我需要一些custome时间戳功能，我正在尝试为它创建一个类。不幸的是，当我试图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。

代码语言：javascript
复制
#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

这个问题发生在我打电话的时候

代码语言：javascript
复制
std::cout << timeStamp.get(-30);

具体而言，在这一点上：

代码语言：javascript
复制
year   = static_cast<std::ostringstream*>( &(std::ostringstream() << (tempTime->tm_year+1900)) )->str();

这是以下方法的一部分：

代码语言：javascript
复制
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

好吧，这让我很奇怪：

当我打电话的时候

代码语言：javascript
复制
std::cout << timeStamp.get();

它在我指示的线路上崩溃了。

当我去的时候

代码语言：javascript
复制
std::string hey = timeStamp.get();
std::cout << hey;

它在第二个__DEBUG__语句上崩溃(就在if(quality)之后)

编辑编辑

errorTime在这里初始化：

代码语言：javascript
复制
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

我试着摆脱花哨的指针工作，让它占用更多的几行。不幸的是，它似乎不起作用：

代码语言：javascript
复制
    /*
    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

哈。所以看起来，ostreamstring并不是这里的罪魁祸首--即使当我将所有OSS功能都删除，并且只是硬编码一个回复时，它也会在这一行崩溃。

这意味着在这个块中：

代码语言：javascript
复制
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";

当我将第一个调试输出调用为

代码语言：javascript
复制
std::string hey = timeStamp.get();
std::cout << hey;

但当我称之为

代码语言：javascript
复制
std::cout << timeStamp.get();

我在后面看到调试输出。

代码语言：javascript
复制
std::string year, month, day, hour, minute, second;
c++
ostringstream
EN

回答 2

Stack Overflow用户

回答已采纳

发布于 2013-12-17 14:37:11

神秘的崩溃和指针一起运行，所以在取消引用之前，请检查tempTime和errorTime是否指向有效对象。发布的代码没有显示初始化tempTime的位置，所以这是开始查找的地方。

除了将值赋值给指针之外，当您使用指针时，还要确保对象的生存期仍然有效。您不希望保存指向已超出作用域的临时对象的指针。

票数 3
EN

Stack Overflow用户

发布于 2013-12-17 13:42:55

这段代码“似乎”是合法的，但在形式上--实际上是不正确的--因为你的地址是临时的。&(std::ostringstream() << (tempTime->tm_year+1900))。

您可以很容易地避免它--只需编写(std::ostringstream() << (tempTime->tm_year+1900)).str()。如果它仍然崩溃--尝试给std::ostringstream()一个名称，如

代码语言：javascript
复制
std::ostringstream() oss;
oss << (tempTime->tm_year+1900);
oss.str();

如果这也无济于事的话-我现在没什么主意了。

票数 2
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/20635413

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