This function or variable may be unsafe. To disable deprecation, use _CRT_SECURE_NO_WARNINGS

Question

I'm working on a C++ DDL, however I get the following issue in some places:

C4996 'sprintf': This function or variable may be unsafe. Consider using sprintf_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

I did try #define _CRT_SECURE_NO_WARNINGS, but the issue remains.
This is the code:

sprintf(szDebugString, "%s: 0x%x (%s%s%i)", ptrName, (DWORD)funcPtr, interfaceName, interfaceVersion.c_str(), i);

Or just pass the `/wd4996` option to `cl`. – David C. Rankin Jul 07 '18 at 05:31 — David C. Rankin, Jul 07 '18 at 05:31

score 13 · Answer 1 · answered Mar 30 '16 at 11:31

13

You have to define _CRT_SECURE_NO_WARNINGS before #include <Windows.h>.

Alternatively, use the safe version:

sprintf_s(szDebugString, sizeof(szDebugString), "%s: 0x%x (%s%s%i)",
    ptrName, (DWORD)funcPtr, interfaceName, interfaceVersion.c_str(), i);

answered Mar 30 '16 at 11:31

trojanfoe

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Or the one present in the standard: `snprintf`. – Martin Bonner supports Monica Mar 30 '16 at 11:46
@MartinBonner Agreed; that is better, however I am unsure if it's available in Visual Studio. – trojanfoe Mar 30 '16 at 11:52
1

Oh gah! See http://stackoverflow.com/questions/2915672/snprintf-and-visual-studio-2010. tl;dr? Not until VS2015. Only 16 years after a sensible set of semantics were standardized! – Martin Bonner supports Monica Mar 30 '16 at 11:56
@MartinBonnersupportsMonica MS were very adamant at that semantics for internal reason. They also were offering different kind of ranged for loop. All because their interbal coding style – Swift - Friday Pie Mar 07 '20 at 15:50

score 5 · Answer 2 · answered Mar 07 '20 at 15:31

5

To turn off the warning for an entire project in the Visual Studio IDE:

1- Open the Property Pages dialog for your project.

2- Select the Configuration Properties > C/C++ > Advanced page.

3- Edit the Disable Specific Warnings property to add 4996. Choose OK to apply your changes.

answered Mar 07 '20 at 15:31

david

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you save me ( this was my first C++ project and you save me ) – ehsan wwe Apr 27 '21 at 14:28
Thank you. The top answer doesn't work for my situation (`sprintf()` is being called by a library and it doesn't include Windows.h) – Charlie Su Feb 02 '23 at 12:08

score 4 · Answer 3 · answered Dec 01 '16 at 09:32

4

put this define into stdafx.h.

E.g.

#pragma once
#define _CRT_SECURE_NO_WARNINGS

#include "targetver.h"

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

answered Dec 01 '16 at 09:32

Vyacheslav

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Amit G. · Answer 4 · 2018-07-07T08:25:26.267

3

In my point of view, on a Windows project, it is not a good idea to disable the warning; a better idea is to improve the code. Mute the warning not just keeps this potential code vulnerability unnoticed, but also blinds programmers when introducing other potential code vulnerabilities.

edited Jul 07 '18 at 08:25

answered Jul 07 '18 at 05:38

Amit G.

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score 0 · Answer 5 · answered Feb 27 '19 at 18:57

From the docs:

You can turn off the warning for a specific line of code by using the warning pragma, #pragma warning(suppress : 4996). You can also turn the warning off within a file by using the warning pragma, #pragma warning(disable : 4996).

https://learn.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-3-c4996?f1url=https%3A%2F%2Fmsdn.microsoft.com%2Fquery%2Fdev15.query%3FappId%3DDev15IDEF1%26l%3DEN-US%26k%3Dk(C4996)%26rd%3Dtrue&view=vs-2017

This function or variable may be unsafe. To disable deprecation, use _CRT_SECURE_NO_WARNINGS

5 Answers5