#include "stdafx.h"
#include
#include
#include
#include
using namespace std;
//newString类实现：一个处理字符串的类
class newString
{
friend ostream& operator<<(ostream&,const newString&);
friend istream& operator>>(istream&,newString&);
public:
const newString& operator=(const newString&);
//返回const引用，禁止(a=b)=c通过
newString(const char *);
//constructor;conversion from the char string
newString();
//default constructor
newString(const newString&);
//copy constructor
~newString();
//destructor
char& operator[] (int);
const char& operator[] (int) const;
//overload the relational operators
bool operator==(const newString&) const;
bool operator!=(const newString&) const;
bool operator<=(const newString&) const;
bool operator >=(const newString&) const;
bool operator<(const newString&) const;
bool operator>(const newString&) const ;
private:
char *strPtr;
int strLength;
};
newString::newString (const char* str)
{
strLength=strlen(str);
strPtr=new char[strLength+1];
assert(strPtr!=NULL);
strcpy(strPtr,str);
}
//default constructor
newString::newString ()
{
strLength=0;
strPtr=new char[1];
assert(strPtr!=NULL);
strcpy(strPtr,"");
}
//copy constructor:use deep copy
newString::newString (const newString& rstr)
{
strLength=rstr.strLength ;
strPtr=new char[strLength+1];
assert(strPtr!=NULL);
strcpy(strPtr,rstr.strPtr);
}
newString::~newString ()
{
delete [] strPtr;
strPtr=NULL;
}
//overload the assignment operator
const newString& newString::operator=(const newString& rStr)
{
if(this!=&rStr)
{
delete [] strPtr;
strLength=rStr.strLength ;
strPtr=new char[strLength+1];
assert(strPtr!=NULL);
strcpy(strPtr,rStr.strPtr );
}
return *this;
}
char& newString::operator[](int index)
{
assert(index>=0 && index return strPtr[index];
}
const char& newString::operator[](int index) const
{
assert(index>=0 && index return strPtr[index];
}
//overload the relational operator
bool newString::operator==(const newString& rStr) const
{
return(strcmp(strPtr,rStr.strPtr )==0);
}
bool newString::operator !=(const newString& rStr) const
{
return !(*this==rStr);
}
bool newString::operator<(const newString& rStr) const
{
return (strcmp(strPtr,rStr.strPtr)<0 );
}
bool newString::operator<=(const newString& rStr) const
{
return (strcmp(strPtr,rStr.strPtr)<=0 );
}
bool newString::operator>(const newString& rStr) const
{
return (strcmp(strPtr,rStr.strPtr)>0 );
}
bool newString::operator>=(const newString& rStr) const
{
return (strcmp(strPtr,rStr.strPtr)>=0 );
}
//overload the stream insertion operator <<
ostream& operator<<(ostream& os,const newString& str)
{
os< return os;
}
istream& operator>>(istream& is,newString& str)
{
char temp[81];
is>>setw(81)>>temp;
//ensure the char string read less than 80
str=temp;
return is;
}
//test program
int main()
{
newString s1="Sunny";
const newString s2("Warm");
newString s3;
newString s4;
cout<<"s1 and s2 are :"<
if(s1<=s2)
cout<<"s1 is less than s2"<
else
cout<<"s2 is less than s1"<
cout<<"enter a string not less than 7 characters:"<
cin>>s1;
cout<<"the new value of s1:"<
s4=s3="Birthday";
cout<<"s3 and s4 are:"<
cout<<"s3[3]="<
s3[3]=s1[2];
cout<<"After s3[3]=s1[2]:"< cout<<"new value of s3 is:"<
return 0;
}
阅读(617) | 评论(0) | 转发(0) |
