C Programming

C26: Examples on Pointer Usage
Determine the output of the following program.

#include <stdio.h>
#include <string.h>

struct  sample {
	char *name;
	int *id;
	float price;
};

static char  product[] = "Greggs Coffee";
static float price1 = 3.20;
static int   id = 773;

void printrecord( struct sample * );

void printrecord( struct sample *goods )
{
	printf("Name = %s\n", goods->name );
	printf("ID = %d\n", *goods->id);
	printf("Price = %.2f\n", goods->price );
	goods->name = &product[0];
	goods->id = &id;
	goods->price = price1;
}

main()
{
	int code = 123, number;
	char name[] = "Apple Pie";
	struct sample item;

	item.id = &code;
	item.price = 1.65;
	item.name = name;
	number = *item.id;
	printrecord( &item );
	printf("Name = %s\n", item.name );
	printf("ID = %d\n", *item.id);
	printf("Price = %.2f\n", item.price );
}

What are we trying to print out?

What does it evaluate to?

eg,

	printf("ID = %d\n", *goods->id);
	%d is an integer
		we want the value to be a variable integer type
	goods->id,
		what is id, its a pointer, so we mean contents of, 
			therefor we use *goods->id
		which evaluates to an integer type

Name = Apple Pie
ID = 123
Price = 1.65

Name = Greggs Coffee
ID = 773
Price = 3.20

 ©Copyright B Brown. 1984-1999. All rights reserved.