Table of Contents
Practice programs on Pointers
1. Program in C to demonstrate how to handle the pointers in the program:
#include <stdio.h>
int main()
{
int* ab;
int m;
m=29;
printf("\n\n Pointer : How to handle the pointers in the program :\n");
printf("------------------------------------------------------------\n");
printf(" Here in the declaration ab = int pointer, int m= 29\n\n");
printf(" Address of m : %p\n",&m);
printf(" Value of m : %d\n\n",m);
ab=&m;
printf(" Now ab is assigned with the address of m.\n");
printf(" Address of pointer ab : %p\n",ab);
printf(" Content of pointer ab : %d\n\n",*ab);
m=34;
printf(" The value of m assigned to 34 now.\n");
printf(" Address of pointer ab : %p\n",ab);
printf(" Content of pointer ab : %d\n\n",*ab);
*ab=7;
printf(" The pointer variable ab is assigned the value 7 now.\n");
printf(" Address of m : %p\n",&m);//as ab contain the address of m
//so *ab changed the value of m and now m become 7
printf(" Value of m : %d\n\n",m);
return 0;
}
*********************************************************************
2. Add two numbers using call by reference:
#include <stdio.h>
long addTwoNumbers(long *, long *);
int main()
{
long fno, sno, sum;
printf("\n\n Pointer : Add two numbers using call by reference:\n");
printf("-------------------------------------------------------\n");
printf(" Input the first number : ");
scanf("%ld", &fno);
printf(" Input the second number : ");
scanf("%ld", &sno);
sum = addTwoNumbers(&fno, &sno);
printf(" The sum of %ld and %ld is %ld\n\n", fno, sno, sum);
return 0;
}
long addTwoNumbers(long *n1, long *n2)
{
long sum;
sum = *n1 + *n2;
return sum;
}**************************************************************
3.Generate permutations of a given string:
#include <stdio.h>
#include <string.h>
void changePosition(char *ch1, char *ch2)
{
char tmp;
tmp = *ch1;
*ch1 = *ch2;
*ch2 = tmp;
}
void charPermu(char *cht, int stno, int endno)
{
int i;
if (stno == endno)
printf("%s ", cht);
else
{
for (i = stno; i <= endno; i++)
{
changePosition((cht+stno), (cht+i));
charPermu(cht, stno+1, endno);
changePosition((cht+stno), (cht+i));
}
}
}
int main()
{
char str[] = "abcd";
printf("\n\n Pointer : Generate permutations of a given string :\n");
printf("--------------------------------------------------------\n");
int n = strlen(str);
printf(" The permutations of the string are : \n");
charPermu(str, 0, n-1);
printf("\n\n");
return 0;
}*******************************************************
4. Store and retrieve elements from an array:
#include <stdio.h>
int main()
{
int arr1[25], i,n;
printf("\n\n Pointer : Store and retrieve elements from an array :\n");
printf("------------------------------------------------------------\n");
printf(" Input the number of elements to store in the array :");
scanf("%d",&n);
printf(" Input %d number of elements in the array :\n",n);
for(i=0;i<n;i++)
{
printf(" element - %d : ",i);
scanf("%d",arr1+i);
}
printf(" The elements you entered are : \n");
for(i=0;i<n;i++)
{
printf(" element - %d : %d \n",i,*(arr1+i));
}
return 0;
}*****************************************************
5. Calculate the length of a string:
#include <stdio.h>
int calculateLength(char*);
void main()
{
char str1[25];
int l;
printf("\n\n Pointer : Calculate the length of the string :\n");
printf("---------------------------------------------------\n");
printf(" Input a string : ");
fgets(str1, sizeof str1, stdin);
l = calculateLength(str1);
printf(" The length of the given string %s is : %d ", str1, l-1);
printf("\n\n");
}
int calculateLength(char* ch) // ch = base address of array str1 ( &str1[0] )
{
int ctr = 0;
while (*ch != '\0')
{
ctr++;
ch++;
}
return ctr;
}
********************************************************************
6. Find the factorial of a given number:
#include <stdio.h>
void findFact(int,int*);
int main()
{
int fact;
int num1;
printf("\n\n Pointer : Find the factorial of a given number :\n");
printf("------------------------------------------------------\n");
printf(" Input a number : ");
scanf("%d",&num1);
findFact(num1,&fact);
printf(" The Factorial of %d is : %d \n\n",num1,fact);
return 0;
}
void findFact(int n,int *f)
{
int i;
*f =1;
for(i=1;i<=n;i++)
*f=*f*i;
}
****************************************************************
7. Sort an array using pointer:
#include <stdio.h>
void main()
{
int *a,i,j,tmp,n;
printf("\n\n Pointer : Sort an array using pointer :\n");
printf("--------------------------------------------\n");
printf(" Input the number of elements to store in the array : ");
scanf("%d",&n);
printf(" Input %d number of elements in the array : \n",n);
for(i=0;i<n;i++)
{
printf(" element - %d : ",i+1);
scanf("%d",a+i);
}
for(i=0;i<n;i++)
{
for(j=i+1;j<n;j++) { if( *(a+i) > *(a+j))
{
tmp = *(a+i);
*(a+i) = *(a+j);
*(a+j) = tmp;
}
}
}
printf("\n The elements in the array after sorting : \n");
for(i=0;i<n;i++)
{
printf(" element - %d : %d \n",i+1,*(a+i));
}
printf("\n");
}
***************************************************************
8. Show a function returning pointer:
#include <stdio.h>
int* findLarger(int*, int*);
void main()
{
int numa=0;
int numb=0;
int *result;
printf("\n\n Pointer : Show a function returning pointer :\n");
printf("--------------------------------------------------\n");
printf(" Input the first number : ");
scanf("%d", &numa);
printf(" Input the second number : ");
scanf("%d", &\numb);
result=findLarger(&numa, &numb);
printf(" The number %d is larger. \n\n",*result);
}
int* findLarger(int *n1, int *n2)
{
if(*n1 > *n2)
return n1;
else
return n2;
}
****************************************************************
9. Sum of all elements in an array:
#include <stdio.h>
void main()
{
int arr1[10];
int i,n, sum = 0;
int *pt;
printf("\n\n Pointer : Sum of all elements in an array :\n");
printf("------------------------------------------------\n");
printf(" Input the number of elements to store in the array (max 10) : ");
scanf("%d",&n);
printf(" Input %d number of elements in the array : \n",n);
for(i=0;i<n;i++)
{
printf(" element - %d : ",i+1);
scanf("%d",&arr1[i]);
}
pt = arr1; // pt store the base address of array arr1
for (i = 0; i < n; i++) {
sum = sum + *pt;
pt++;
}
printf(" The sum of array is : %d\n\n", sum);
}
****************************************************************
10. Print all the alphabets:
#include <stdio.h>;
int main()
{
char alph[27];
int x;
char *ptr;
printf("\n\n Pointer : Print all the alphabets:\n");
printf("----------------------------------------\n");
ptr = alph;
for(x=0;x<26;x++)
{
*ptr=x+'A';
ptr++;
}
ptr = alph;
printf(" The Alphabets are : \n");
for(x=0;x<26;x++)
{
printf(" %c ", *ptr);
ptr++;
}
printf("\n\n");
return(0);
}
****************************************************************************
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