C + + learning (13)

1 //design of String class2 //1. String literals can be used in a string compatible with the C language3 //2. Overloaded logic equals operator (= =)4 //3. String manipulation involves taking string lengths and fetching substrings5#include <string.h>6#include <iostream.h>7#include <stdlib.h>8 classstring{9     Private:Ten         Char*str; One         intsize; A      Public: - //String (); -String (Char*s=""); theString (ConstString &s); -~String (); -  -         intLength ()Const; +String SubStr (intPosintlength); -  +String &operator=(ConstString &s); AString &operator=(Char*s); at  -         int operator==(ConstString &s)Const; -         int operator==(Char*s)Const; -  -Friendint operator==(Char*strl,ConstString &STRR); - }; in  - //string::string () {} toString::string (Char*s) { +      This->size=strlen (s) +1; -Str=New Char[size]; the strcpy (str,s); * } $ Panax NotoginsengString::string (ConstString &s) { -      This->size=s.size;  theStr=New Char[size]; +     if(str==NULL) { AExit0); the     } +      for(intI=0; i<size;i++){ -          This->str[i]=S.str[i]; $     } $ } -  -string::~String () { the     Delete[] This-str; - }Wuyi  the  - intString::length ()Const{ Wu     return  This-size; - } About  $String String::substr (intPosintlength) { -     intcharsleft=size-pos-1; - String temp; -     Char*p,*Q; A  +     if(pos>=size-1){ the         returntemp; -     } $     if(Length>charsleft) {//length cannot go beyond range theLength=Charsleft; the     } the     Delete[]temp.str; the      -Temp.str=New Char[length+1]; in  thep=Temp.str; theq=& This-Str[pos]; About  the      for(intI=0; i<length;i++){ the*p++=*q++; the     } +          -*p=NULL; thetemp.size=length+1;Bayi      the     returntemp; the } -  -String &string::operator=(ConstString &s) { the     if( This->size!=s.size) { the         Delete[]str; the          This->str=New Char[s.size]; theSize=s.size; -     } the      for(intI=0; i<s.size;i++){ the          This->str[i]=S.str[i]; the     }94     return* This; the  the } the 98String &string::operator=(Char*s) { About     intLength=strlen (s); -     if( This->size!=length) {101         Delete[] This-str;102Str=New Char[length+1];103          This->size=length+1;104     } thestrcpy This-str,s);106     return* This;107 }108 109 intString::operator==(ConstString &s)Const{//String class and String class compared the     returnstrcmp This-&GT;STR,S.STR) = =0;111 } the intString::operator==(Char*s)Const{//String class and C language string comparison113     returnstrcmp This->str,s) = =0; the } the  the int operator==(Char*strl,ConstString &AMP;STRR) {//c preload string and string class comparison117     returnstrcmp (strl,strr.str) = =0;118 }119  - intMain () {121 122String str1 ("Data Structure");123String str2 ("Structure");124 String STR3,STR4,STR5; the 126Cout<<str1. Length () <<Endl;127      -Str3=str1. SUBSTR (5,9);129Str4=str1. SUBSTR (5,9); thestr5="Structure";131  the     if(str3==STR4) {133cout<<"String and string string comparisons"<<Endl;134     }135 136     if(str5=="Structure"){137cout<<"String and C strings compared"<<Endl;138     }139     if("strcture"==str2) { $cout<<"C-language strings and string comparisons"<<Endl;141     }142     return 0;143}

C + + learning (13)