用c++实现的String类

#include<iostream.h> #include<stdlib.h> #include<string.h> #include"Strclass.h" //出错报告函数 void String::Error(int errorType, int badIndex) const { if (errorType == outOfMemory) cerr << "Memory exhausted!" << endl; else cerr << "Index " << badIndex << " out of range" << endl; exit(1); } //带默认形参的构造函数 String::String(char *s) { size=strlen(s);//*s的长度,不计算'\0'在内 str=new char[size+1];//需要开辟size+1个空间,因为还要存放'\0' if(str==null) Error(outOfMemory); char *srcptr=s;//用临时指针做复制,不改变原来指针str和s的位置 char *desptr=str; for(int i=0;i<size+1;i++)//共复制size+1次,把'\0'也复制过去 *desptr++ = *srcptr++; } //拷贝构造函数 String::String(const String& s) { size=s.Length();//size值为串s的长度,'\0'也计算在内 str=new char[size+1];//这里也得开辟size+1个空间 if(str==null) Error(outOfMemory); char *srcptr=s.str; char *desptr=str; for(int i=0;i<size+1;i++) *desptr++ = *srcptr++; } //析构函数 String::~String(void) { delete [] str; } //重载赋值运算符,String=String String& String::operator= (const String& s) { int flag=0; int n=s.Length();//源串s的长度 if(size<n)//若目的串的长度小于源串的长度,删除原有存储空间,重新分配和源串相同大小的存储空间 { delete [] str; str=new char[n+1]; if(str==null) Error(outOfMemory); size=n; flag=1;//用flag区分,因为若目的串小于原串,最后还得赋值'\0' } char *srcptr=(char *)s;//利用重载的指针转换运算符char *,也可以直接用s.str(直接访问私有成员?),不知道为什么 char *desptr=str; for(int i=0;i<n;i++) *desptr++ = *srcptr++; if(flag==1)//若目的串小于源串,最后把'\0'放进去 *desptr='\0'; return(*this); } //重载赋值运算符,String=C++String String& String::operator = (char *s) { int flag=0; int n=strlen(s);//源串s的长度 if(size<n)//若目的串的长度小于源串的长度,删除原有存储空间,重新分配和源串相同大小的存储空间 { delete [] str; str=new char[n+1]; if(str==null) Error(outOfMemory); size=n; flag=1;//用flag区分,因为若目的串小于原串,最后还得赋值'\0' } char *srcptr=s; char *desptr=str; for(int i=0;i<n;i++) *desptr++ = *srcptr++; if(flag==1)//若目的串小于源串,最后把'\0'放进去 *desptr='\0'; return(*this); } //重载运算符"==",string==String int String::operator== (const String& s) const { if(size!=s.Length())//先比较大小 return(0); char *sptr=(char *)s; for(int i=0;i<size;i++) if(*str!=*sptr) return(0); return(1); } //重载运算符"==",String==C++String int String::operator== (char *s) const { if(size!=strlen(s))//先比较大小 return(0); char *sptr=s; for(int i=0;i<size;i++) if(*str!=*sptr) return(0); return(1); } //重载运算符"=="为友元函数,C++String==String int operator== (char *str, const String& s) { if(strlen(str)!=s.Length())//先比较大小 return(0); char *sptr1=str; char *sptr2=(char *)s; for(int i=0;i<strlen(str);i++) if(*sptr1!=*sptr2) return(0); return(1); } //重载运算符"!=",string==String int String::operator!= (const String& s) const { if(size!=s.Length())//先比较大小 return(1); char *sptr=(char *)s; for(int i=0;i<size;i++) if(*str!=*sptr) return(1); return(0); } //重载运算符"!=",String==C++String int String::operator!= (char *s) const { if(size!=strlen(s))//先比较大小 return(1); char *sptr=s; for(int i=0;i<size;i++) if(*str!=*sptr) return(1); return(0); } //重载运算符"!="为友元函数,C++String==String int operator!= (char *str, const String& s) { if(strlen(str)!=s.Length())//先比较大小 return(1); char *sptr1=str; char *sptr2=(char *)s; for(int i=0;i<strlen(str);i++) if(*sptr1!=*sptr2) return(1); return(0); } //重载运算符"<",String<String int String::operator< (const String& s) const { char *sptr1=str; char *sptr2=(char *)s; for(;*sptr1!='\0' && *sptr2!='\0';sptr1++,sptr2++) if(*sptr1<*sptr2) return(1); else if(*sptr1>*sptr2) return(0); if(*sptr1=='\0' && *sptr2!='\0')//前面都相同,sptr1串短,所以sptr1小 return(1); else return(0); } //重载运算符"<",String<C++String int String::operator< (char *s) const { char *sptr1=str; char *sptr2=s; for(;*sptr1!='\0' && *sptr2!='\0';sptr1++,sptr2++) if(*sptr1<*sptr2) return(1); else if(*sptr1>*sptr2) return(0); if(*sptr1=='\0' && *sptr2!='\0')//前面都相同,sptr1串短,所以sptr1小 return(1); else return(0); } //重载运算符"<"为友元函数,C++String<String int operator< (char *str, const String& s) { char *sptr1=str; char *sptr2=(char *)s; for(;*sptr1!='\0' && *sptr2!='\0';sptr1++,sptr2++) if(*sptr1<*sptr2) return(1); else if(*sptr1>*sptr2) return(0); if(*sptr1=='\0' && *sptr2!='\0')//前面都相同,sptr1串短,所以sptr1小 return(1); else return(0); } //重载运算符"<=",String<=String int String::operator<= (const String& s) const { if(str<s || str==s) return(1); else return(0); } //重载运算符"<=",String<=C++String int String::operator<= (char *s) const { if(str<s || str==s) return(1); else return(0); } //重载运算符"<="为友元函数,C++String<=String int operator<= (char *str, const String& s) { if(str<s || str==s) return(1); else return(0); } //重载运算符">",String>String int String::operator> (const String& s) const { if(str<=s) return(0); else return(1); } //重载运算符">",String>C++String int String::operator> (char *s) const { if(str<=s) return(0); else return(1); } //重载运算符">"为友元函数,C++String>String int operator> (char *str, const String& s) { if(str<=s) return(0); else return(1); } //重载运算符">=",String>=String int String::operator>= (const String& s) const { if(str>s || str==s) return(1); else return(0); } //重载运算符">=",String>=C++String int String::operator>= (char *s) const { if(str>s || str==s) return(1); else return(0); } //重载运算符">="为友元函数,C++String>=String int operator>= (char *str, const String& s) { if(str>s || str==s) return(1); else return(0); } //重载串接运算符"+",String+String String String::operator+ (const String& s) const { int n=size+s.Length(); char *sum=new char[n+1];//多分配一个空间给'\0' char *desptr=sum; char *srcptr1=str; char *srcptr2=(char *)s; for(int i=0;i<size;i++)//复制本串 *desptr++ = *srcptr1++; for(i=0;i<s.Length();i++)//复制串s *desptr++ = *srcptr2++; *desptr='\0';//最后把'\0'放进去 return String(sum);//返回时创建临时对象,更高效 } //重载串接运算符"+",String + C++String String String::operator+ (char *s) const { int n=size+strlen(s); char *sum=new char[n+1];//多分配一个空间给'\0' char *desptr=sum; char *srcptr1=str; char *srcptr2=s; for(int i=0;i<size;i++)//复制本串 *desptr++ = *srcptr1++; for(i=0;i<strlen(s);i++)//复制串s *desptr++ = *srcptr2++; *desptr='\0';//最后把'\0'放进去 return String(sum);//返回时创建临时对象,更高效 } //重载串接运算符"+"为友元函数,C++String+String String operator+ (char *str,const String& s) { int n=strlen(str)+s.Length(); char *sum=new char[n+1];//多分配一个空间给'\0' char *desptr=sum; char *srcptr1=str; char *srcptr2=(char *)s; for(int i=0;i<strlen(str);i++)//复制串str *desptr++ = *srcptr1++; for(i=0;i<s.Length();i++)//复制串s *desptr++ = *srcptr2++; *desptr='\0';//最后把'\0'放进去 return String(sum);//返回时创建临时对象,更高效 } //重载串接运算符"+=",String += String void String::operator+= (const String& s) { char *srcptr1=new char[size];//先保存原目的串为srcptr1 for(int i=0;i<size;i++) *srcptr1++ = *str++; srcptr1-=size;//srcptr1指针归位 //delete [] str; str=new char[size+s.Length()+1];//多分配一个空间给'\0' char *desptr=str; char *srcptr2=(char *)s; for(i=0;i<size;i++) *desptr++ = *srcptr1++; for(i=0;i<s.Length();i++) *desptr++ = *srcptr2++; *desptr='\0';//最后把'\0'放进去 size+=s.Length()