I am using c++. I want to build code which contains memcpy_s on linux. I am using gcc 9.3. I made some modifications.

#ifdef __cplusplus
extern "C" {
#define _STDC_WANT_LIB_EXT1_ 1
#include <string.h>
}
#endif

void doMemCopy(char* buf, size_t buf_size, char* in, int chr) {
    memcpy_s(buf, buf_size, in, chr);
}

I use CMakelist file, like:

set(CMAKE_C_FLAGS_RELEASE   "-MD -Ob3 -O2 -fp:fast -JMC- -DNDEBUG -utf-8")
set(CMAKE_CXX_FLAGS_RELEASE "-MD -Ob3 -O2 -fp:fast -JMC- -DNDEBUG -utf-8")

set(CMAKE_C_STANDARD   11)
set(CMAKE_CXX_STANDARD 17)

It gives me this error: error: ‘memcpy_s’ was not declared in this scope; did you mean ‘memcpy’? What am I doing wrong.