Why is this double type variable default to int when passed as a function parameter?

Question

I am learning C and was trying to help debug a friends code. He was defining his function parameters in the global scope and then passing them into the function def like so:

#include <stdio.h>

double x;


double myfunc(x){
    return x;    
}

void main(){

}

I get this is wrong, but not why the following error comes up:

main.c:14:8: warning: type of ‘x’ defaults to ‘int’ [-Wimplicit-int] 

Can someone help me understand how the computer is interpreting this code?

Answer 1

He was defining his function parameters in the global scope

No, he does not.

The global x is unrelated to the function's parameter x.

The former is a global double, the latter is local to the function and, as the compiler is warning, "defaults to int".

I get this is wrong

It is not wrong, but not possible.