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Simple C++ question

Posted on 2013-01-28
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Last Modified: 2013-01-28
Hello experts,

please have a look at the code below:

#include <iostream>
#include <cstring>
using namespace std;

//tworze klase, ktora umozliwi dodawanie stringow oraz
//zapis stringow w postaci zmienna = "jakis string";

class String{
	char * string;

public:
	String(const char* aChar){
		string = new char[????];   how can I determine the length of aChar here?
		strcpy(string, aChar);
		cout<<string<<endl;
	}

	~String(){
		delete string;
		string = 0;
	}

	char * getString(){
		return string;
	}

	void operator = (char * aString){
		strcpy(string, aString);
	}

	friend ostream& operator<< (ostream & aOstream, const String & aString);

};

ostream& operator<< (ostream & aOstream, const String & aString){
	aOstream << aString.string;
	return aOstream;
}

int main(){
	String string1("kdjshfgkljs");
	String string2("skldjhfls");

	cout << string1 << string2;

	return 0;
}

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Thank you

panJames
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Comment
Question by:panJames
  • 2
2 Comments
 
LVL 31

Accepted Solution

by:
Zoppo earned 2000 total points
ID: 38827233
Hi panJames,

you can use strlen, i.e.:
string = new char[strlen(aChar)+1]; // need to add 1 for terminating NUL character

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Hope that helps,

ZOPPO
0
 
LVL 31

Expert Comment

by:Zoppo
ID: 38830005
BTW, two more points:

1. In the constructor you should check if the passed string is a valid pointer.
2. The assignment operator isn't correctly implemented, it doesn't (re-)allocate the memory needed.

So I would change these two functions to look like this:
	String(const char* aChar){
		if ( aChar != 0)
		{
			string = new char[strlen(aChar)];
			strcpy(string, aChar);
			cout<<string<<endl;
		}
		else
		{
			string = 0;
			cout << "empty string"<< endl;
		}
	}

	void operator = (char * aString)
	{
		delete [] string;
		string = 0;

		if ( aString != 0)
		{
			string = new char[strlen(aString);
			strcpy(string, aString);
		}
	}

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