/* Call By Value -- A copy of the argument is made and is passed to the 
   parameter.
*/

#include <stdio.h>

/* Function Prototype. It is "heading" of function. 
   It is typically placed above any Function Definitions,
   but below #include and #define.
*/
int sqr(int t); 

int main(void)
{
	int t;
	printf("Caculating an integer's square.\n");
	printf("Please enter an integer: ");
	scanf("%d", &t);

	printf("%d's square is %d.\n", t, sqr(t)); //function invocation

	return 0;
}

/* calculating t's square */
int sqr(int t)
{
        return t*t;
} 

/* Note: Change made to the parameter have NO effect on the argument,
         i.e., the parameter is implemented as a local variable which is
         initialized to the value passed from the argument.
*/