Question

Here’s a sample program:

#include <stdio.h>

void foo(int b[]){
    printf("sizeof in foo: %i\n", sizeof b);
}

int main(){
    int a[4];
    printf("sizeof in main: %i\n", sizeof a);
    foo(a);
}

The output is:

sizeof in main: 16
sizeof in foo: 8

Question is, what’s the point of that syntax if it’s just converted to a standard pointer at the function boundary?

Answer 1

1. It’s syntactic sugar: void foo(int b[]) suggests that b is going to be used as an array (rather than a single out-parameter), even though it really is a pointer.

2. It’s a left-over from early versions of C, where postfix [] was the syntax for a pointer declaration.