Stray error when returning array using function in C

Question

I have been trying to return back an array using the code below -

#include <stdio.h>

int* factor(int num);

int main(void)
{
    int num;
    printf("\nEnter a number: ");
    scanf("%d", &num);
    int* array;
    array = factor(num);
    for(int counter=0; counter<num; counter++)
    {
        printf("%d\n", array[counter]);
    }
}

int* factor(int num)
{
   int NumberArray[100];
   for(int i=0; i<num; i++)
   {
       NumberArray[i] = i;
   }
   return NumberArray;
}

And this has generated the following output -

gcc assignment3func.c -o assignment3func
assignment3func.c: In function ‘factor’:
assignment3func.c:19:1: error: stray ‘\302’ in program
    int NumberArray[100];
 ^
assignment3func.c:19:1: error: stray ‘\240’ in program
assignment3func.c:19:1: error: stray ‘\302’ in program
assignment3func.c:19:1: error: stray ‘\240’ in program
assignment3func.c:23:11: warning: function returns address of local variable [-Wreturn-local-addr]
    return NumberArray;
           ^

Please help me out. I couldn't understand the stray thing.

Answer 1

That array is declared with automatic storage duration, so when it goes out of scope, it is deallocated by your compiler. If you want to create an array that you can return, allocate it with dynamic memory.

int* NumberArray = malloc(sizeof(int)*100);

Answer 2

In response to your question about how to return an array without using malloc:

#include <stdio.h>
void factor(int num, int *NumberArray); //pass a pointer to an array to the function
int main(void)
{
  int num;
  printf("\nEnter a number:");
  scanf("%d",&num);
  int array[100]; //create the array in the calling function
  factor(num, array);
  for(int counter=0;counter<num;counter++)
  {
      printf("%d\n",array[counter]);
  }
}
void factor(int num, int *NumberArray)
{
   for(int i=0; i<num; i++){
       NumberArray[i] = i;
   }
}

Here you create the array in the calling function and pass a pointer to it in the called function. The called function then operates on the array that is scoped in the calling function.

Answer 3

The "stray '\302'"/"stray '\240'" messages are about having extra non-printing (invisible) Unicode characters in your source code. These usually come about from copy-pasting code from some other source.

Specifically, the two-byte \302\240 sequence is a UTF-8 encoding for a non-breaking space character. Unfortunately, deleting these with your editor can be tricky as they are invisible! If you can put your editor into ASCII mode instead of Unicode, they may show up so you can delete them.