Sample of Identifier Scopes

int XX, YY, ZZ;   // global variable declarations

void F1(void);    // function declaration
void F2(void);    // function declaration

void main(void)
{
  // local variables in main
  int x, y, z;  
	
  x = XX;   // Ok, XX is in global scope
  F1();     // Ok, F1 is in global scope

  z = z1;   // Error, z1 is local to F1
  z = z2;   // Error, z2 is local to F2
}

void F1(void)
{
  // local variables in F1
  int x1, y1, z1; 

  y1 = YY;  // Ok, YY is in global scope
  F2();     // Ok, F2 is in global scope
  x1 = x;   // Error, x is local to main
}

void F2(void)
{
  // local variables in F2
  int x2, y2, z2;

  z2 = ZZ;  // Ok, ZZ is in global scope
  y2 = y1;  // Error, y1 is local to F1
  F1();     // Ok, F1 is in global scope
}