/************************************************************************ *
The following statement calls the function startup and
passes no parameters:
startup();
The following function call causes copies of a and b to be stored in a
local area for the function sum. The function sum runs using the copies of a
and b.
sum(a, b);
The following function call passes the value 2 and the value of the
expression a + b to sum:
sum(2, a + b);
The following statement calls the function printf, which receives a
character string and the return value of the function sum, which
receives the values of a and b:
printf("sum = %d\n", sum(a,b));
The following program passes the value of count to the
function increment. increment increases the value of the parameter x by 1.
* ************************************************************************/
/**
** This example shows how a parameter is passed to a function
**/
#include <stdio.h>
void increment(int);
int main(void)
{
int count = 5;
/* value of count is passed to the function */
increment(count);
printf("count = %d\n", count);
return(0);
}
void increment(int x)
{
++x;
printf("x = %d\n", x);
}
/************************************************************************ *
The output illustrates that the value of count in main remains unchanged:
x = 6 count = 5
In the following program, main passes the address of
count to increment. The function increment was changed to handle the pointer
. The parameter x is declared as a pointer. The contents to which x points
are then incremented.
* ************************************************************************/
/**
** This example shows how an address is passed to a function
**/
#include <stdio.h>
int main(void)
{
void increment(int *x);
int count = 5;
/* address of count is passed to the function */
increment(&count);
printf("count = %d\n", count);
return(0);
}
void increment(int *x)
{
++*x;
printf("*x = %d\n", *x);
}
/************************************************************************ *
The output shows that the variable count is increased:
*x = 6 count = 6
* ************************************************************************/