Question

I was trying to return an array from child_prog() to main(). The code looks like this:

#include<stdio.h>
#include<stdlib.h>
int* child_prog(int some_input);

void main(void){
  int C[10];
  int some_input;
  C = child_prog(some_input);
}

int* child_prog(int some_input){
  static int out[10];
  // ...
  // ... some wizardry
  return out;
}

Now the compiler generates an error saying that it can not assign to C (which is an int[] type) the value returned from child_prog (which is an int* type). Indeed, the program works fine when I make C an int* and malloc it 10 ints of memory. But I don’t understand why the compiler can’t assign to C (an array defined as C[10] and hence a pointer) the value returned from child_prog (an array defined as static int out[10] and hence again a pointer).

Answer 1

1. You cannot assign to an array. You need to memcpy it.
2. int* != int[] while the first is a pointer that might point to an int of a sequence of ints, the second is a sequence of ints
3. You can use int *C; and pass the length of the array (if unknown at compile time) as an out parameter.
4. static int out[10]; is not a malloced, but static.