Coding problem

**shady_shockerz** · 01-07-2009

HI I have worte a code and the code looks a bit messed I need to simplify it. I need to insert std::string in the program too but I am not sure whether to do it or not can someone please guide me through please....

Code:

#ifndef RSTRING_H
#define RSTRING_H
#include <stdlib.h>
#include <iostream>
#include <string>
#include <cmath>
;

class RString{
	char* name;
	int length;
	int getLength()
{ 
return length;
}
	char* getName()
{
return name;
}
public:
	RString()
{
name="";
length=0;
}
	RString(const char* S)
      {
	length=strlen(S) + 1;
	name = new char[length];
	strcpy(name,S);
	}
	RString(char * a,char * b)
{
	length=strlen(a)+strlen(b)+1;
	name=new char[length];
	strcpy(name,a);
	strcat(name,b);
	}
	RString(int value){
	int i= (int)(log10(value)+1.0);
	length=i;
	name=new char[i+1];
	itoa((int) value,name,10);
	}

	void add(char *a){
		char* tmp=new char[length+1];
		strcpy(tmp,name);
		delete name;
		length+=+strlen(a);
		name=new char[length+1];
		strcpy(name,tmp);
		strcat(name,a);
		delete [] tmp;
	}
	
	void add(int value){
		char* tmp=new char[length+1];
		strcpy(tmp,name);
		delete name;
	 	int i= (int)(log10(value)+2.0);
		length+=i;
		name=new char[length+1];
		char* iSt=new char[i];
		itoa((int) value,iSt,10);
		strcpy(name,tmp);
		strcat(name,iSt);
		delete [] tmp;
	}
	RString(RString* a,RString* b)
{
		int len=a->getLength()+b->getLength();
		if(len>100)
{
			cerr<<"String too long;";
			exit(-1);
		}
		char tmp[100];
		strcpy(tmp,a->getName());
		strcat(tmp,b->getName());
		name=tmp;
		length=len;
	}
	
	~RString() { delete name; }

	char * print(){return name;}
}

;
endif

**hk_mp5kpdw** · 01-07-2009

What do you mean by "insert std::string into the program"?

Better formatting of the posted code would help a bit.

This:

Code:

~RString() { delete name; }

Should be:

Code:

~RString() { delete [] name; }

This:

Code:

#include <stdlib.h>

Should be:

Code:

#include <cstdlib>

Although I don't really see why you really need that at all for the code shown.

Given all the C-style string function calls you probably also want to have:

Code:

#include <cstring>

This:

Code:

int getLength()
{ 
    return length;
}

Should be a const function:

Code:

int getLength() const
{ 
    return length;
}

These:

Code:

char* getName()
{
return name;
}

char * print(){return name;}

Are basically the same except for the name and one being public and the other private. Returning a straight char* can be dangerous, you're exposing the classes internals to direct manipulation by the user. A const char* would be somewhat better.

Code:

#ifndef RSTRING_H
#define RSTRING_H
#include <stdlib.h>
#include <iostream>
#include <string>
#include <cmath>
;

...

}

;
endif

Typos?

**shady_shockerz** · 01-07-2009

Hi,

Thanks for replying actually this code was written in I dont know what language! I have to rectify this code and make it into C++ for better understanding and i am clueless and dont knw from where should I start? Thats y i need ur help

**shady_shockerz** · 01-07-2009

Originally Posted by shady_shockerz

Hi,

Thanks for replying actually this code was written in I dont know what language! I have to rectify this code and make it into C++ for better understanding and i am clueless and dont knw from where should I start? Thats y i need ur help

Another Issue is

Code:

int main()
{
    RString s("abc");
    RString t = s;
}

This two line program has a double deletion error when the program terminates. This three line program has both a double deletion error and memory leaks:

Code:

int main()
{
    RString s("abc");
    RString t("123");
    t = s;
}

Not being able to do simple copies makes a string class basically useless. But I dont know how to solve the problem. Can someone help me with this one

**King Mir** · 01-08-2009

Can't you just use std::string instead of RString, and therefore not worry about converting it. Why do you need RString?

**laserlight** · 01-08-2009

Originally Posted by shady_shockerz

Not being able to do simple copies makes a string class basically useless. But I dont know how to solve the problem. Can someone help me with this one

Since your RString class performs manual memory management, you should provide the copy constructor, copy assignment operator and destructor. You provided the destructor (though implemented incorrectly, as hk_mp5kpdw pointed out), but did not provide (or disable, but that does not make sense here) the other two.

I note that your add() member functions are a little too complicated: you only need to use new[] and delete[] once.

You also have another problem where if you default construct an RString object and it is destroyed immediately after, you would then attempt to use delete[] on a pointer that points to a string literal ("").

**shady_shockerz** · 01-09-2009

Hi Laserlight,

I saw a interesting observation but I dont know how to implement it can you please elobarate how to do it??

**laserlight** · 01-09-2009

Originally Posted by shady_shockerz

I saw a interesting observation but I dont know how to implement it can you please elobarate how to do it??

As you have been told in another forum, you need to go through at least one good book on C++.

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