CODEWITHSUNDEEP
c++visual-c++msvcrt
Perry
Perry

Reputation: 1217

get length of formatted string before format with security enhancements

I want to convert my code from "unsecure" version to "secure" to avoid an error and the define:

int l = sprintf(NULL, "%.*f", precision, newVal);
char* msg = (char*)malloc(l + 1);
sprintf(msg, "%.*f", precision, newVal);

error 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.

My problem is if I write this:

int l = sprintf_s(NULL, 0, "%.*f", precision, newVal);
char* msg = (char*)malloc(l + 1);
sprintf_s(msg, l, "%.*f", precision, newVal);

An exception is fired:

Unhandled exception at 0x00007FFFEA83924C (ucrtbased.dll) in WinTests.exe: An invalid parameter was passed to a function that considers invalid parameters fatal.

So, how is it supposed to be done?

Upvotes: 0

Views: 87

Answers (0)

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