Visual C++ CRT build error(C4996) issue

Hi everyone!

In this article, I’d like to talk about Visual C++ CRT build error(C4996). The build error occurs when we use C runtime library(CRT). I always use _CRT_SECURE_NO_WARNINGS macro for the issue.

At first, I made a VC++ project on visual studio community 2013 as follows.

Menu -> File -> Project

Templates -> Visual C++ -> Win32 -> Win32 Console Application

Build and run. it just do nothing.

Next, I added include and function calls. And build.

// ConsoleApplication1.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

#include <stdio.h>
#include <string.h>

int _tmain(int argc, _TCHAR* argv[])
{
	char str[10];

	strcpy(str, "hello!");
	printf("%s", str);

	return 0;
}

A build error occurred as follows.
error C4996: ‘strcpy’: This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

What should we do? The link below is MSDN about this issue.
Security Features in the CRT

using _s functions
We can use strcpy_s instead of strcpy.
strcpy_s(str, “hello!”);

The function strcpy_s is more secure version. So we should use strcpy_s instead of strcpy.

It is certainly so.

But, if we have open source library source, we have to update the source. It needs time to update. Or I think that when we start to study C language programing, we use without _s functions.

_CRT_SECURE_NO_WARNINGS
I always define _CRT_SECURE_NO_WARNINGS to use old CRT functions. There are some ways to define. I always insert the definition in stdafx.h as follows.

#pragma once

#define _CRT_SECURE_NO_WARNINGS 1 // <--- this line

#include "targetver.h"

#include <stdio.h>
#include <tchar.h>

After that we can use unsafe CRT functions. But we should remember that the security issues still exist.

 - Visual C++