Swap() func in the book Essential C does not compile

Question

wtf.c:11:6: error: expected declaration specifiers or '...' before '&' token Swap(&a, &b);

wtf.c:11:10: error: expected declaration specifiers or '...' before '&' token Swap(&a, &b);

Did not want to resort to StackOverflow for my personal problem but i cannot figure it out. The code is exactly the same as the book's. I've also tried making separated pointers and using them as arguments but i get the same error. Can someone shine some light on what am i doing wrong? I'm using gcc to compile the code.

static void Swap(int *x, int *y){
  int temp;
  temp = *x;
  *x = *y;
  *y = temp;
}

int a = 1;
int b = 2;

Swap(&a, &b);

I expected it to compile at least the exact example from the book but apparently not even that's possible.

Answer 1

#include <stdio.h>

static void Swap(int *x, int *y){
  int temp;
  temp = *x;
  *x = *y;
  *y = temp;
}

int main()
{
  int a = 1;
  int b = 2;

  Swap(&a, &b);
  printf("%d %d\n", a, b);
  return 0;
}

That compile and the execution print "2 1", as you can see swap works

---

You had the compiler errors because of the form Swap(&a, &b); which is not a declaration nor a definition (it is a function call)

As it is said in remark the entry point of any C program is the function main, automatically called, for more read documentation about C