自己实现的string类代码,C代码库,德仔网

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【C】自己实现的string类
作者:LAST_MAN / 发布于2012/6/25/ 602
<div>class _string
{
friend std::istream& operator>>(std::istream& is, _string& a);
friend std::ostream& operator<<(std::ostream& os,_string& a);

public:
_string() //????????
{ 
length = 0;
b=new char[1];
b[0]='\0';
 } 
_string(char *a); //??????
_string(int n,char a);
~_string(); //????????
 _string(_string &a); //?????????
 int size(){return length;} //????????
 _string operator+(const _string& a); //????'+'??????
 _string& operator+=(const _string& a); //????'+='??????
 _string& operator=(const _string& a); //????????????
 char& operator[]( int n); //?????&plusmn;??????
 _string substr(int pos,int n); //?????????
 _string substr(int pos); //?????????</div>
<div>
private:
char *b;
int length;
};
</div>
<div></div>
<div>
<div></div>
<div></div>
<div>// _string.cpp : ??????????&oacute;????????
//</div>
#include "stdafx.h"
#include<iostream>
#include<string.h>
#include"_string.h"
#include<stdlib.h>
using namespace std;</div>
<div>_string::_string(char *a) //??????
{
length = strlen(a); 
b = new char[length+1];
for(int i= 0;i<length;i++)
{
b[i] = a[i];
}
b[length] = '\0';
}
<div>_string::_string(int n,char a)
{
b=new char[n+1];
for(int i= 0;i<n;i++)
{
b[i] =a;
}
b[n] = '\0';
}
<div>_string::~_string()
{
delete []b;
length=0;
}
<div>_string::_string(_string &a)
{
length=a.size();
b=new char [length+1];
 for(int i = 0;i<length;i++)
{
b[i] = a.b[i];
}
b[length] = '\0';
}
<div>_string _string::operator+(const _string& a)
{
int newLen = length+a.length;
char *str;
str = new char[newLen+1];
int count = 0;
for(int i = 0;i<length;i++)
{
str[i] = this->b[i];
count++;
}

for(int i =0;count<newLen;count++,i++)
{
str[i] = a.b[i];
}
str[newLen] = '\0';
_string temp(str);

return temp;
}
<div>_string& _string:: operator+=(const _string& a) 
{
int newLen = length+a.length;
char *str;
str = new char[newLen+1];
int count = 0;
for(int i = 0;i<length;i++)
{
str[i] = this->b[i];
count++;
}

for(int i =0;count<newLen;count++,i++)
{
str[i] = a.b[i];
}
str[newLen] = '\0';
_string temp(str);
*this=temp;
return *this;
 }
_string& _string:: operator=(const _string &a)
 {
 if(this==&a)
 return *this;</div>
<div> delete []b;
 length = a.length;
 b = new char[length+1];
 for(int i = 0;i<length;i++)
{
b[i] = a.b[i];
}
b[length] = '\0';
 return *this;</div>
<div>}
<div> char& _string:: operator[]( int n)
 {
 if(n>length)
 return b[length-1];
 else
 return b[n];
 }
<div> ostream& operator<<(ostream& os, _string& a)
 {
 os<<a.b;
 return os;
 }
 istream& operator>>(std::istream& is, _string& a)
 { 
 is>>a.b ;
 a.length=strlen(a.b);
 return is;
 }
<div>_string _string::substr(int pos, int n)
 {
 char *p = new char[n+1];
 for(int i=0;i<n;i++)
 {
 p[i]=b[pos];
 pos++;
 }
 p[n]='\0';
 _string k(p);
 k.length=n;
 return k;
}
 
_string _string::substr(int pos)
{
 int len=length;
 char *p=new char[len-pos+1];
 int t=pos;
 for(int i=0;t<len;t++,i++)
 {
 p[i]=b[t];
 }
 p[t]='\0';
 _string k(p);
 k.length=len-pos;
 return k;
}
<div></div>
<div></div>
<div></div>
#include "stdafx.h"
#include<iostream>
#include"_string.h"</div>
<div>using namespace std;
int main()
{
/*_string a("1234");
cout<<a.size()<<endl;
_string b("5678");
a+=b;
cout<<a.size()<<endl;
_string aa("111");
_string bb("222");
 _string c;
c=aa+bb;
cout<<"c size 1 "<<c.size()<<endl;
 c=aa;
cout<<"c size 2 "<<c.size()<<endl;
 c="1234567";
cout<<"c size 3 "<<c.size()<<endl;
cout<<c<<endl;
_string xxx(10,'2');
cout<<"xxx is "<<xxx<<endl;
_string str;
 cout<<"??????str"<<endl;
cin>>str;
cout<<"?????????:";
cout<<str<<endl;
cout<<"?????????????: "<<str.size()<<endl;
cout<<"substr"<<endl;
_string abc("1234567");
_string xx=abc.substr(3,3);
cout<<"xx is "<<xx<<endl;
_string qq=abc.substr(3);
cout<<"qq is "<<qq<<endl;*/
_string a;
cin>>a;
cout<<a;
return 0;
}
<div></div>
<div></div>
<div>// stdafx.h : ??????????????????
// ?????????&otilde;?????????
// ??????????????
//</div>
<div>pragma once</div>
#include "targetver.h"</div>
#include <stdio.h>
#include <tchar.h></div>
<div></div>
<div>// TODO: ???????&oacute;????????????????
</div>
<div></div>
<div></div>
<div>// stdafx.cpp : ???????????????????
// _string.pch ???????????
// stdafx.obj ????????????????</div>
#include "stdafx.h"</div>
<div>// TODO: ?? STDAFX.H ??
// ?????&kappa;?????????????????????????????</div>
</div>
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