Thread: Mysterious Crash

So I am doing a problem from C How To Program 7th Edition by Deitel. The problem is 8.10 for those who might have access to the book.

In a nutshell, I am comparing strings up to n characters. The program funs fine however at the end it crashes. I cannot figure out why

Code:

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

int main(void){

    char *string1, *string2;

    int n, compare;

    puts("Enter a string");
    fgets(string1,20, stdin);

    puts("Enter a string");
    fgets(string2,20, stdin);

    puts("Enter the amount of characters to compare");
    scanf("%d",&n);

    compare = strncmp(string1, string2, n);

    if(compare == 0)
        printf("Strings compares are equal\n");
    else
        printf("string 1 is %s String 2\n", (compare > 0) ? "greater than" : "less than");

    printf("Ending ....\n");

    return 0;
}