Operator overloading []

operator.cpp

#include <iostream>
#include <string.h> 
using namespace std;

class SubString;
class String{
	public:
		char *str;
		size_t size; //len +1
    	String(const char *s);
     void append(const String &other);
		String(bool dummy,const char *s);
		String(size_t n, char c);
		String(String const & obj);
		String& operator=(const String & obj);
		SubString operator[](int i) const;
		~String();
				
};
class SubString{
	public:
		char *str;
		int offset;
		size_t size; //len +1
		SubString(int i,const char *s);
		SubString(size_t n, char c);
		SubString(SubString const & obj);
		SubString& operator=(const SubString & obj);
		String operator[](int i) const;
		~SubString();
};


	String::String(bool dummy, const char *s=""){
		
			size=strlen(s);
		    str=new char[size+1];
			for(int i=0;i<(signed)size+1;++i){
				*(str+i)=*(s+i);
			}
			
		}
	
		SubString String:: operator[](int i) const{
			char stroka[this->size-i+1];
			for(int k=0;k<((signed)this->size-i+1);++k){
				stroka[k]=*(this->str+i+k);
			}
			return SubString(i,stroka);
		}
		

				



	SubString::	SubString(int i, const char *s=""){
	
		offset=i;
			size=strlen(s);
		    str=new char[size+1];
			for(int i=0;i<(signed)size+1;++i){
				*(str+i)=*(s+i);
			}
		
		
		}
	SubString::	SubString(size_t n, char c){
				size=n;
		    str=new char[size+1];
			for(int i=0;i<(signed)size;++i){
				*(str+i)=c;
			}
			*(str+size)='\0'; 
		}
		SubString::SubString(SubString const & obj){
			this->		size=obj.size;
			char *stroka=new char[size+1];
			this->str=stroka;
			strcpy(str,obj.str);
		}
		SubString& SubString:: operator=(const SubString & obj){
			delete [] str;
			this->		size=obj.size;
			str=new char[size+1];
			strcpy(str,obj.str);
			return *this;
		}
		String SubString:: operator[](int i) const{
			if(i-offset==1) return String(0,"");
			char stroka[i-offset+1];
			for(int k=0;k<i-offset;++k){
				stroka[k]=*(this->str+k);
			}
			stroka[i-offset]='\0';
			return String(0,stroka);
		}
		
	
		SubString::~SubString(){
			
			delete [] str;
		}