报错求助

[specter1210]

引用

#include "stdafx.h"
#include <iostream>
#include <time.h>
#include   <string>  
using namespace std;


string& TiHuan(string& str,const string& old_date,const string& new_date)     
	{   
    for(string::size_type pos(0);pos!=string::npos;pos+=new_date.length())   
	{     
        if(   (pos=str.find(old_date,pos))!=string::npos   )     
            {
				str.replace(pos,old_date.length(),new_date);     
			}
		else   
			break;     
    };     
    return   str;     
	}; 

int main(void)
{
	

	//Son.ShowTheData(10);
	//char i_date[1096]={0};
	char *i_date=NULL;
	//char DateBuffer[50]={0};
	char Month[20]={0};
	time_t TheDate;
	time(&TheDate);
    printf("time is: %s", ctime(&TheDate));
	memcpy(i_date,ctime(&TheDate) + 4,20);
	//memcpy(Month,ctime(&TheDate) + 4,3);
	string Date = "12345";
	Date = i_date;

	TiHuan(Date,"Jan","01");
	TiHuan(Date,"Feb","02");
	TiHuan(Date,"Mar","03");
	TiHuan(Date,"Apr","04");
	TiHuan(Date,"May","05");
	TiHuan(Date,"Jun","06");
	TiHuan(Date,"Jul","07");
	TiHuan(Date,"Aug","08");
	TiHuan(Date,"Sep","09");
	TiHuan(Date,"Oct","10");
	TiHuan(Date,"Nov","11");
	TiHuan(Date,"Dec","12");
	const char *DateBuffer = Date.c_str();
	cout<<"date is:"<<Date<<endl;
	//memcpy(DateBuffer,i_date,20);
	if(strncmp(DateBuffer,"09 05 14:35:03 2016",20) > 0) //Mon Dec 05 14:35:03 2016
	{
		cout<<"time is over"<<endl;
	}
	else
	{
		cout<<"u can use it"<<endl;
	};

	system("pause");

	return 0;
};

报错
0x0ff9caa8 (msvcr100d.dll) 处最可能的异常: 0xC0000005: 写入位置 0x00000000 时发生访问冲突
0x101acaa8 (msvcr100d.dll) 处有未经处理的异常: 0xC0000005: 写入位置 0x00000000 时发生访问冲突

麻烦大神帮忙看看

[qq_32148499]

你的i_date是个空指针啊，肯定报错了

[赵4老师]

崩溃的时候在弹出的对话框按相应按钮进入调试，按Alt+7键查看Call Stack即“调用堆栈”里面从上到下列出的对应从里层到外层的函数调用历史。双击某一行可将光标定位到此次调用的源代码或汇编指令处，看不懂时双击下一行，直到能看懂为止。

[小灸舞]

你尝试对一个空指针进行写入或者解引用操作就会出现这个错误。
单步调试和设断点调试（VS IDE中编译连接通过以后，按F10或F11键单步执行，按Shift+F11退出当前函数；在某行按F9设断点后按F5执行停在该断点处。）是程序员必须掌握的技能之一。

[paschen]

因为你的i_date还没有指向有效的对象，你就调用memcpy(i_date,ctime(&TheDate) + 4,20); char *i_date=NULL; 改成： char i_date[1000];

[specter1210]

谢谢