Solution for Exercise 20-8

ex2008

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

int main()
{
    char *input;
    int len;

    /* allocate storage */
    input = (char *)malloc(sizeof(char)*1024);
    if(input==NULL)
    {
        puts("Unable to allocate buffer! Oh no!");
        exit(1);
    }
    
    /* gather input */
    puts("Type something long and boring:");
    fgets(input,1023,stdin);

    /* resize the buffer */
    len = strlen(input);
    input = realloc(input,sizeof(char)*(len+1));
    if( input==NULL )
    {
        puts("Unable to reallocate buffer!");
        exit(1);
    }
    puts("Memory reallocated.");

    /* output results */
    puts("You wrote:");
    printf("%s",input);

    return(0);
}

Output

Type something long and boring:
Is this long enough and boring enough for you?
Memory reallocated.
You wrote:
Is this long enough and boring enough for you?

Notes

* The input buffer is resized and any excess storage is released for use again.

* This method of reallocation is often how programs efficiently manage storage. After all, storing a short string of text in a 1K buffer is a waste of space. Here you see how the storage can be modified so that only what's necessary is used.

* The realloc() function can both increase and decrease a buffer's size. Specify the new buffer size as the second argument, and you're good to go.

Exercise ex2009 →