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Started by nivlekio Mar 9, 2008 at 10:10 PM 3 replies 700+ views

Original Post

Mar 9, 2008 at 10:10 PM

Hey guys why does this not work? all i get is NULL....


#include <windows.h>
#include <iostream>
#include <stdio.h>

using namespace std;


void main()
{
	char szChar[256];
	string sAlias = "Nivlekio";

	sprintf_s(szChar,sizeof(szChar), "Alias: %s", sAlias);

	while(1)
	{
		cout << szChar;
	};
}

ChaosEngine

784

ChaosEngine

Mar 9, 2008 at 10:21 PM

because std::string is not a char array.if you must do this, use c_str() as follows

sprintf_s(szChar,sizeof(szChar), "Alias: %s", sAlias.c_str());

However, the correct C++ way is to use a stringstream.

#include <string>#include <iostream>#include <sstream>using namespace std;int main() // NEVER use void main(){    stringstream stream;    string alias = "Nivlekio";    stream << "Alias: " << alias;    cout << stream.str();}

Shorter, safer and standard compliant.

Rydinare

Mar 9, 2008 at 10:23 PM

Quote:
Original post by nivlekio
Hey guys why does this not work? all i get is NULL....

*** Source Snippet Removed ***

First, don't do this. If you're using C++ constructs, use full C++ constructs. You're better off using std::ostringstream instead of sprintf and always use std::strings over raw strings.

That being said, the reason why this didn't work is that you used the format specifier of %s, yet you provided a C++ string class instead of a raw string. You'd need to do sAlias.c_str() in your sprintf_s call, instead of just sAlias. That's one major downside of using unsafe calls like sprintf is that you leave the world of type safety.