为什么函数的类型冲突会导致Clang错误？

Question

I have seen a similar question like this on this site, and everyone basically said to change the function's name that was in conflict with stdio.h .

However, I have changed every function's name multiple times and it still gives me this error. But why?

Answer 1

Never post the code in the image .

The problem is that you call functions that main() hasn't seen before, so do:

float getCelcious(void);

int main(void) {
  ...
}

float getCelcious(void) {
  ...
}

Take a look here please: Function Declaration and Function Prototypes .