wap to realloc program using C.


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


int main()
{
    /* Define required variables */
    char *ptr1, *ptr2;
    size_t length1, length2;

    /* Define the amount of memory required */
    length1 = 10;
    length2 = 30;

    /* Allocate memory for our string */
    ptr1 = (char *)malloc(length1);

    /* Check to see if we were successful */
    if (ptr1 == NULL)
    {
        /* We were not successful, so display a message */
        printf("Could not allocate required memory\n");

        /* And exit */
        exit(1);
    }

    /* Copy a string into the allocated memory */
    strcpy(ptr1, "This is good ");

    /* Oops, we wanted to say more but now do not
     have enough memory to store the message! */

    /* Expand the available memory with realloc */
    ptr2 = (char *)realloc(ptr1, length2);

    /* Check to see if we were successful */
    if (ptr2 == NULL)
    {
        /* We were not successful, so display a message */
        printf("Could not re-allocate required memory\n");

        /* And exit */
        exit(1);
    }

    /* Add the rest of the message to the string */
    strcat(ptr2, " and better way");

    /* Display the complete string */
    printf("%s\n", ptr2);

    /* Free the memory we allocated */
    free(ptr2);
    getch();

    return 0;
} 

OUTPUT: