C function - Pass by value? Pass By Ref?

Hi Guys,

Look at the following code; Why doesnt it indicate whether its passed by val or pass by ref (by using the '&' operator?)? Or by default C is passed by ref?

Are there some default rules somehow?

Please advise

Code:

---

/*********************************************************************
 *
 * Purpose: Reverse characters in a string.
 * Author:  K&R
 * Date:   
 *
 *********************************************************************/

void reverse(char s[]);

main()
{
  char text[80]="martin";

  printf("string is %s\n", text);
  reverse(text);
  printf("string is %s\n", text);
}

void reverse(char s[])
{
  int c, i, j;
 
  for (i=0, j=strlen(s)-1; i < j;i++, j--)
  {
    c = s[i];
    s[i] = s [j];
    s[j] = c;
  }
}

---

C always passes by value. There is no such thing as by 'reference' in C. You can use pointers to pass the value of a variable's address, and dereference that to access a variable, simulating by 'reference', but it's still actually by value.

Arrays are always passed as pointers to their first element. So any array you pass to a function, if changes are made inside the function to it, will affect the actual array outside of the function.


Quzah.

Edit: Oops, too late, and I think you mean passes by value in the first sentence, Quzah :P

C is always, always pass by value.

When you pass an array to a function, you are actually passing the address of the first element, so in the above case, you are effectively passing &text[0], or the address of the letter 'm' in "martin". Because the function has the address, any modification to the array in the function is to the array that was passed.

oooh! :D

Alright. Understand! :D

Thanks!

>>C always passes by reference.
Dont mix beer and C.Afterall its beer effect :D