Error messages.

Question

Error messages.

Lisa Settevig 21

I'm getting the following message 'StrType3\StrType3.cpp(19,5): 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.' And with 'strcat'. I have the following includes in the program <string> & <cstring>. I've entered this program from a book - 'C++ Primer Plus, 6th edition.'

Thank you.

RLWA32 49,536 Reputation points

2021-07-20T09:55:31.227+00:00

While the more secure "_s" versions of CRT string functions are recommended to help avoid buffer overruns if the sample code from your book uses the old functions simply changing function names in the book's code to use the secure versions may not be enough for the code from the book to successfully compile. The CRT headers include overloads for the secure versions so that it is not necessary to explicitly pass the size of the receiving buffer to the function if the buffer is declared as an array (e.g., char buf[10]). On the other hand, if the receiving buffer is a pointer (e.g., char*) then the size of the buffer must be explicitly passed to the secure versions.

So while the secure versions are recommended for good reason, using _CRT_SECURE_NO_WARNINGS avoids the need to make any changes to the book's sample code.

Accepted answer

2 additional answers

Your answer

RLWA32 49,536 Reputation points

2021-07-20T09:55:31.227+00:00

While the more secure "_s" versions of CRT string functions are recommended to help avoid buffer overruns if the sample code from your book uses the old functions simply changing function names in the book's code to use the secure versions may not be enough for the code from the book to successfully compile. The CRT headers include overloads for the secure versions so that it is not necessary to explicitly pass the size of the receiving buffer to the function if the buffer is declared as an array (e.g., char buf[10]). On the other hand, if the receiving buffer is a pointer (e.g., char*) then the size of the buffer must be explicitly passed to the secure versions.

So while the secure versions are recommended for good reason, using _CRT_SECURE_NO_WARNINGS avoids the need to make any changes to the book's sample code.

Answer 1

Hi,

I suggest you could refer to the Doc: Compiler Warning (level 3) C4996

To fix a C4996 issue, we usually recommend you change your code. Use the suggested functions and global variables instead. If you need to use the existing functions or variables for portability reasons, you can turn off the warning.

According to the error message, I suggest you could try to use strcpy_s instead of strcpy.

You could also try to turn off deprecation warnings for these functions in the CRT via define _CRT_SECURE_NO_WARNINGS.

For more details I suggest you could refer to the link: https://learn.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-3-c4996?view=msvc-160#unsafe-crt-library-functions

Best Regards,

Jeanine

If the response is helpful, please click "Accept Answer" and upvote it.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Jeanine Zhang-MSFT 11,356 Reputation points Microsoft External Staff

2021-07-23T08:25:31.777+00:00

@Lisa Settevig

May I know if you have got any chance to check my answer? I am glad to help if you have any other questions.

Answer 2

RLWA32 49,536

Well, the error message gave you the solution. Insert #define _CRT_SECURE_NO_WARNINGS in your source file prior to including any header files.

Answer 3

Lisa Settevig 21

Thanks for your help.

Share via

Error messages.

2 additional answers

Your answer