Returning Arrays/Pointers from a function

Question

I am trying to create a new integer array which is derived from a string of characters. For example :

char x[] = "12334 23845 32084";  

int y[] = { 12334, 23845, 32084 };

I am having trouble understanding how to return an array ( which I understand isn't possible ) from a function.

I originally tried :

/* Convert string of integers into int array. */
int * splitString( char string[], int n )
{
    int newArray[n];

    // CODE

    return ( newArray );
}

int main( void )
{
    int x[n] = splitString( string, n );

    return ( 0 );
}

I later learned that you can not do this.

How do pointers work in regards to functions?

Thank you.

Answer 1

Typically, you require the caller to pass in the result array.

void splitString( const char string[], int result[], int n) {
    //....
}

This is advantageous because the caller can allocate that memory wherever they want.

Answer 2

The problem is you're returning a pointer to something on the stack. You need to create your array on the heap, then free it when you're done:

int * splitString( char string[], int n )
{
    int *newArray = malloc(sizeof(int) * n);

    // CODE

    return ( newArray );
}

int main( void )
{
    int *x = splitString( string, n );

    // use it

    free(x);

    return ( 0 );
}