MSVC: error C4996: 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead

Meaning

Microsoft marks functions without bounds checking as unsafe. The message suggests the _s variant, which is not portable. The better fix is a bounded standard alternative (snprintf, std::string, std::copy). You can silence it with _CRT_SECURE_NO_WARNINGS, but you then keep the buffer-overflow risk.

Common causes

• Using strcpy, strcat, sprintf, scanf, fopen, getenv in a project with SDL checks enabled
• Visual Studio project defaults (/sdl) turning warnings into errors
• std::copy/std::equal with raw pointers (checked iterators warning C4996)
• Deprecated POSIX names such as strdup, read, open

Detailed fix by platform

Code examples

#include <cstdio>
#include <string>

int main() {
    char buf[16];
    // strcpy(buf, "hello");                      // C4996 on MSVC
    std::snprintf(buf, sizeof buf, "%s", "hello"); // bounded and portable
    std::string s = "hello";                       // best: no buffer at all
}

How to diagnose

1. Function — Which function is flagged?
2. Settings — SDL checks or warnings-as-errors on?
3. Portability — Must the code also build on Linux/macOS?

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