Printing pointers:
A program that prints out pointers and the values they point to:
#include <stdio.h>
int main()
{
int a = 10, b = 2;
int *p1, *p2;
p1 = &a;
p2 = &b;
printf("%p %p \n", p1, p2);
printf("%d %d \n", *p1, *p2);
return 0;
}
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This will produce following result:
0xbfffdac4 0xbfffdac0
10 2
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Passing pointers as parameters:
A program that swaps integers using a function that accepts pointers to the integers to be swapped:
#include <stdio.h>
void swap(int * q,int * p)
{
int temp = *p;
*p = *q;
*q = temp;
}
int main()
{
int a = 10, b = 2, x = 3, y = 5;
printf("a,b,x,y: %d,%d,%d,%d\n", a, b, x, y);
swap(&x, &y);
swap(&a, &b);
printf("a,b,x,y: %d,%d,%d,%d\n", a, b, x, y);
}
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It will produces following result:
a,b,x,y: 10,2,3,5
a,b,x,y: 2,10,5,3
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Passing pointers as parameters:
A program that computes the area and perimeter of a rectangle:
#include <stdio.h>
void rectangle(int a, int b, int * area, int * perim);
int main()
{
int x, y;
int area, perim;
printf("Enter two values separated by space: " );
scanf("%d %d", &x, &y);
rectangle(x, y, &area, &perim);
printf("Area is %d Perimeter is %d\n", area, perim);
return 0;
}
void rectangle(int a,int b,int * area,int * perim)
{
*area = a * b;
*perim = 2 * (a + b);
}
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This will produce following result:
Enter two values separated by space: 10 15
Area is 150 Perimeter is 50
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Passing arrays as parameters:
A program that reads elements and assign them in an array. Then, it prints the array elements out.
#include <stdio.h>
void get_array(int a[], int size);
void prt_array(int a[], int size);
#define SIZE 10
int main()
{
int a[SIZE];
get_array(a, SIZE);
prt_array(a, SIZE);
printf("\n");
return 0;
}
void get_array(int a[], int size)
{
int i;
printf("Enter 10 values, after each value press enter:\n " );
for (i = 0; i < size; i++)
scanf("%d", &a[i]);
}
void prt_array(int a[], int size)
{
int i;
printf("Printing all values :\n");
for (i = 0; i < size; i++)
printf("%d\n", a[i]);
}
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This will produce something like:
Enter 10 values, after each value press enter:
10
2
3
4
5
6
7
8
9
10
Printing all values :
10
2
3
4
5
6
7
8
9
10
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