运算符重载string运算符.docx

运算符重载

#include<iostream>
#include"FunnyString.h"
using std::istream;
using std::ostream;
using std::string;
using std::cout;
using std::cin;
using std::endl;

int main()
{
FunnyString string1,string2;
cout<<"Please input s1: ";
cin>>string1;
cout<<"Please input s2: ";
cin>>string2;
cout<<"未进行s1-=s2运算时的s1 * s2 is "<<string1*string2;
cout<<"\ns1 + s2 is "<<string1+string2;
cout<<"\ns1 - s2 is "<<string1-string2;
cout<<"\ns1+= s2 is "<<(string1+=string2);
cout<<"\ns1 -= s2 is "<<(string1-=string2);//老师，题目中写道：s1+= s2 is abcabf s1 -= s2 is c s1 * s2 is adbacbdf
cout<<"\n进行s1-=s2运算后的s1 * s2 is "<<string1*string2<<"\n"; //但是"-="后s1的只有一个c了，乘以s2后是不是应为cdabf。
return 0;
}

#include <iostream>

using std::istream;
using std::ostream;
using std::string;
using std::cout;
using std::cin;
using std::endl;
#include"FunnyString.h"

void FunnyString::setFunnyString( const char * a)
{
sPtr=new char [length+1];
if ( a!=0)
strcpy(sPtr,a);
else
sPtr[0]='\0';
}

FunnyString::FunnyString( const char *first)
: length((first!=0)?strlen(first):0)
{
setFunnyString(first);
}
FunnyString::FunnyString( const FunnyString &a)
{
length=a.length;
sPtr=new char[length+1];
for(int i=0;i<length;i++)
sPtr[i]=a.sPtr[i];

}

int FunnyString::getLength() const
{
return length;
}
FunnyString::~FunnyString()
{
delete []sPtr;
}

ostream &operator<<( ostream &output, const FunnyString &a )
{
for (int i=0;i<a.length;i++)
output<<a.sPtr[i];
return output;
}

istream &operator>>( istream &input, FunnyString &a)
{
char b[100];
input>>b;
a.length=strlen(b);
delete []a.sPtr;
a.sPtr=new char [a.length+1];
for (int i=0;i<strlen(b);i++)
{
a.sPtr[i]=b[i];
}

return input;
}

const FunnyString &FunnyString::operator= (const FunnyString &a)
{
if (&a != this)
{
delete []sPtr;
length=a.length;
setFunnyString(a.sPtr);
return *this;
}
else
return *this;
}
const FunnyString &FunnyString::operator+=( const FunnyString &a )
{
FunnyString c;
c=*this+a;
*this=c;
return *this;

}
const FunnyString &FunnyString::operator-=( const FunnyString &a )
{
FunnyString c;
c=*this-a;
*this=c;
return *this;

}

const FunnyString operator+(const FunnyString &left,const FunnyString &right)
{
int len=left.length+right.length;
char *a=new char [len+1];
a[1]=left.sPtr[1];

for (int i=0;i<left.length;i++)
{
a[i]=left.sPtr[i];
}
len=left.length;
int j;

for ( j=0;j<right.length;j++)
{
if(len!=0)
{
if (left.sPtr[len-1]==right.sPtr[j])
{
len--;
}
else
{ j++;
break;
}
}
else
{
j++;
break;
}

}
j--;
if (j<right.length-1)
{
for (;j<right.length;j++)
{
len++;
a[len-1]=right.sPtr[j];
}
}
a[len]='\0';
FunnyString c(a);
delete []a;

return c;
}

const FunnyString operator-(const FunnyString &left,const FunnyString &right)
{
char *a=new char [left.length+1];
int len=left.length;
for (int i=0;i<left.length;i++)
{
a[i]=left.sPtr[i];
}
for (int j=0;j<right.length;j++)
for (int p=0;p<left.length;p++)
{
if (a[p]==right.sPtr[j])
a[p]='0';
}
for (int s=0;s<left.length;s++)
{
if (a[s]=='0')
{
int q=s;
for(;q<left.length;q++)
a[q]=a[q+1];
len--;
s--;
}
}
a[len]='\0';
FunnyString c(a);
delete []a;
return c;
}

const FunnyString operator*(const FunnyString &left,const FunnyString &right)
{
char *a=new char [left.length+right.length+1];
int min;
if (left.length<right.length)
min=left.length;
else
min=right.length;
for (int i=0;i<min;i++)
{
a[2*i]=left.sPtr[i];
a[2*i+1]=right.sPtr[i];
}
if (left.length<right.length)
{
for (int j=min;j<right.length;j++)
{
a[min+j]=right.sPtr[j];
}
}

else
{
for (int j=min;j<left.length;j++)
{
a[min+j]=left.sPtr[j];
}
}
a[left.length+right.length]='\0';
FunnyString c(a);
delete []a;
return c;
}

#ifndef FUNNYSTRING_H
#define FUNNYSTRING_H
#include <iostream>
#include<iomanip>
using std::istream;
using std::ostream;
using std::string;
using std::cout;
using std::cin;
using std::endl;

class FunnyString {

friend ostream &operator<<( ostream &, const FunnyString &);
friend istream &operator>>( istream &, FunnyString &);
friend const FunnyString operator+(const FunnyString &,const FunnyString &);
friend const FunnyString operator-(const FunnyString &,const FunnyString &);
friend const FunnyString operator*(const FunnyString &,const FunnyString &);

public:
FunnyString( const char * ="" );
FunnyString( const FunnyString & );
~FunnyString();
const FunnyString &operator+=( const FunnyString & );
const FunnyString &operator-=( const FunnyString & );
const FunnyString &operator=(const FunnyString &);

int getLength() const;

private:
int length;
char *sPtr;
void setFunnyString( const char * );
};
#endif