Xcode中的Strcpy

Question

This is my code

char strings[10][10] = {"aaa", "bbb", "ccc"};
strcpy(strings[0], strings[0]);

I create a C project in Xcode, and then I run it which will be crash. But if it is a Objective-C project, it will be no problem

Answer 1

Calling strcpy when source and destination are overlapping (or identical as in your case) is undefined behaviour in C, C++, Objective-C and Objective-C++. Undefined behaviour means "anything can happen". "Anything" includes crashing with one compiler and not crashing with another compiler. It also includes worse things.

Answer 2

if it is a C project, the strcpy will be replaced by #if __has_builtin(__builtin___strcpy_chk) || defined(__GNUC__) #if __has_builtin(__builtin___strcpy_chk) || defined(__GNUC__) #undef strcpy #define strcpy(dest, src) \\ __builtin___strcpy_chk (dest, src, __darwin_obsz (dest)) #endif