[Solved] How to use _CRT_SECURE_NO_WARNINGS

I have compile error in my simple MFC window application generated from wizard with several lines of code:

error C4996: ‘strncpy’: This function or variable may be unsafe. Consider using strncpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

I set Configuration Properties>>C/C++>>Preporocessor>>Preprocessor Definitions>> _CRT_NONSTDC_NO_WARNINGS

But this does’t helped. I have another very close project that generates only warning in this place and it has no _CRT_NONSTDC_NO_WARNINGS definition.

Only difference between projects is several different options in wizard.

Why _CRT_NONSTDC_NO_WARNINGS does not helps in first project and why second project compiles without problems without this definition?

Enquirer: vico


Solution #1:

Add by

Configuration Properties>>C/C++>>Preporocessor>>Preprocessor

screenshot of the relevant config interface

Respondent: Balu

Solution #2:

Under “Project -> Properties -> C/C++ -> Preprocessor -> Preprocessor Definitions” add _CRT_SECURE_NO_WARNINGS

Respondent: nexusclarum

Solution #3:

If your are in Visual Studio 2012 or later this has an additional setting ‘SDL checks’ Under Property Pages -> C/C++ -> General

Additional Security Development Lifecycle (SDL) recommended checks; includes enabling additional secure code generation features and extra security-relevant warnings as errors.

It defaults to YES – For a reason, I.E you should use the secure version of the strncpy. If you change this to NO you will not get a error when using the insecure version.

SDL checks in vs2012 and later

Respondent: kmcnamee

Solution #4:

For a quick fix or test, I find it handy just adding #define _CRT_SECURE_NO_WARNINGS to the top of the file before all #include

#include ...
int main(){
Respondent: Carlosio

Solution #5:

Adding _CRT_SECURE_NO_WARNINGS to Project -> Properties -> C/C++ -> Preprocessor -> Preprocessor Definitions didn’t work for me, don’t know why.

The following hint works:
In stdafx.h file, please add


before include other header files.

Respondent: user2703790

Solution #6:

I was getting the same error in Visual Studio 2017 and to fix it just added #define _CRT_SECURE_NO_WARNINGS after #include "pch.h"

#include "pch.h"
Respondent: molecoder

Solution #7:

Visual Studio 2019 with CMake

Add the following to CMakeLists.txt:

Respondent: rbento

The answers/resolutions are collected from stackoverflow, are licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0 .

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