关于CString的类
这两天看了高质量c++编程,我把里面关于Cstring的实现自己在VC6.0中试了一下:
//myString.h
#include "stdafx.h "
class myString
{
public:
myString(const char * str=NULL);
myString(const myString &other);
~myString(void);
myString & operator =(const myString &other);
private:
char *m_data;
};
//mystring.cpp
#include "stdafx.h "
#include "string.h "
#include "mycstring.h "
myString::myString(const char * str)
{
if (str == NULL)
{
m_data = new char(1);
*m_data = '\0 ';
}
else
{
int len = strlen(str);
m_data = new char(len+1);
strcpy(m_data,str);
}
}
myString::myString(const myString &other)
{
int len = strlen(other.m_data);
m_data = new char(len+1);
strcpy(m_data,other.m_data);
}
myString::~myString(void)
{
delete m_data;
//m_data = 0;
}
myString & myString::operator =(const myString &other)
{
if (this == &other) {
return *this;
}
delete [] m_data;
m_data = new char(strlen(other.m_data)+1);
strcpy(m_data,other.m_data);
return *this;
}
// main 函数
#include "stdafx.h "
#include "mycstring.h "
int main(int argc, char* argv[])
{
myString *mystr1= new myString( "dddddddd ");
delete mystr1;//出错
return 0;
}
出错的提示信息为:
DAMAGE: after Normal block(#54) at 0x00431860
我在内存中看了0x00431860 这个地址 就是 mystr1 的 m_data 指向的位置.里面存放的就是字符串 "dddddddd "
[解决办法]
myString::myString(const char * str)
{
if (str == NULL)
{
m_data = new char(1); //应为 m_data = new char[1];
*m_data = '\0 ';
}
else
{
int len = strlen(str);
m_data = new char(len+1); ////应为 m_data = new char[len+1];
strcpy(m_data,str);
}
}
myString::myString(const myString &other)
{
int len = strlen(other.m_data);
m_data = new char(len+1); //应为 m_data = new char[len+1];
strcpy(m_data,other.m_data);
}
......................
myString & myString::operator =(const myString &other)
{
...................
m_data = new char(strlen(other.m_data)+1);
//应为 m_data = new char[strlen(other.m_data)+1];
strcpy(m_data,other.m_data);
return *this;
}
[解决办法]
m_data = new char(len+1) <==> new char[1];*m_data=len+1;
new char[n]就是想要的效果：new n个char
[解决办法]
new char(n); 是申请一个char内存，置它的值为n
new char[n]; 是申请n个char内存
------解决方案--------------------
这种错误不可能在编译时候给出提示 ...
[解决办法]
1.申请新资源时用new char[n];
2.析构函数时delete [] m_data;
[解决办法]
new char() 申请一个char型值为 ' '的字符
new char[] 是申请一个char的动态数组
