C Language: Pointers 29

Examples of realoc() function

Question:
C program to take input for “n” elements by allocating the memory dynamically. Store the elements and display them, further change the size using realloc() function and store elements and display them.
Sol:

#include<stdio.h>
#include<stdlib.h>
int  main()
{
  int n,i,*p,n1;
  char ch;
   printf("Enter total elements ");
   scanf("%d",&n);
   p=(int*)malloc(p*sizeof(int));
   /* or */
   /* p=(int*)calloc(p,sizeof(int)); */
   if(p==NULL)
   {
     printf("Memory allocation failed\n");
     getch();
     exit(1);//header file : stdlib.h
   }
   for(i=0;i<n;i++)
   {
     printf("Enter the element ");
     scanf("%d",(p+i));
   }
   for(i=0;i<n;i++)
   {
     printf("%d\n",*(p+i));
   }
   printf("Enter new size ");
   scanf("%d",&n1);
   p=(int*)realloc(p,sizeof(int));
   if(p==NULL)
   {
     printf("Memory allocation failed\n");
     getch();
     exit(1);//header file : stdlib.h
   }
   for(i=n;i<n1;i++)
   {
     printf("Enter the element ");
     scanf("%d",(p+i));
   }
   for(i=0;i<n1;i++)
   {
     printf("%d\n",*(p+i));
   }
  
   free(p);
 
  return(0);

}

/* Output */
Enter total elements 2
Enter the element 10
Enter the element 20
10
20
Enter new size 5
Enter the element 30
Enter the element 40
Enter the element 50
10
20
30
40
50

Question:
C program to take input for “n” elements by allocating the memory dynamically. Store the elements and display, further change the size using realloc() function and store elements and display them also display sum of all the elements.
Sol:

#include<stdio.h>
#include<stdlib.h>
int  main()
{
  int n,i,*p,n1,s=0;
  char ch;
   printf("Enter total elements ");
   scanf("%d",&n);
   p=(int*)malloc(p*sizeof(int));
   /* or */
   /* p=(int*)calloc(p,sizeof(int)); */
   if(p==NULL)
   {
     printf("Memory allocation failed\n");
     getch();
     exit(1);//header file : stdlib.h
   }
   for(i=0;i<n;i++)
   {
     printf("Enter the element ");
     scanf("%d",(p+i));
   }
   for(i=0;i<n;i++)
   {
     printf("%d\n",*(p+i));
     s=s+*(p+i);
   }
   printf("Sum = %d\n",s);
   printf("Enter new size ");
   scanf("%d",&n1);
   p=(int*)realloc(p,sizeof(int));
   if(p==NULL)
   {
     printf("Memory allocation failed\n");
     getch();
     exit(1);//header file : stdlib.h
   }
   for(i=n;i<n1;i++)
   {
     printf("Enter the element ");
     scanf("%d",(p+i));
   }
   s=0;
   for(i=0;i<n1;i++)
   {
     printf("%d\n",*(p+i));
     s=s+*(p+i);
   }
   printf("Sum = %d\n",s);
   free(p);
 
  return(0);

}

/* Output */
Enter total elements 2
Enter the element 10
Enter the element 20
10
20
Sum = 30
Enter new size 5
Enter the element 30
Enter the element 40
Enter the element 50
10
20
30
40
50
Sum = 150