Ytukyg

When debugging the following code, The debugger point to the line(The line that I commented it out in the last function "printResults" below), But couldn't figure out what is the problem and why the debugger point to that line.

#include <stdio.h>

#include <string.h>

#include <stdbool.h>

#include <stdlib.h>



#define BUFFER_SIZE 256





void swap(char** a, char** b) {

    char* temp = *a;

    *a = *b;

    *b = temp;

}



char* getLongestString(char** strings, int size) {

    char* max = strings[0];

    for (int i = 1; i < size; i++) {

        if (strlen(max) < strlen(strings[i])) {

            max = strings[i];

        }

    }

    return max;

}



void sortStrings(char** strings, int size) {

    bool changed = true;

    while (changed) {

      changed = false;

        for (int i = 0; i < size - 1; i++) {

          if (strcmp(strings[i], strings[i + 1]) >= 0) {

            swap(&strings[i], &strings[i + 1]);

            changed = true;

          }

        }

    }

}



int readSize() {

  int size = 0;

  printf("Enter number of strings:n");

  scanf("%d", &size);

  return size;

}



void printResults(char** words, int size) {

    char* longest = getLongestString(words, size);

    printf("The longest word is: %sn", longest);

    sortStrings(words, size);

    //printf("The maximal word lexicographically is: %sn", words[size]);

    printf("The minimal word lexicographically is: %sn", words[0]);

}

Think that the deceleration of array when you declare an array you do not count index 0 as first element
but when you using the address of that data first index get's in consideration for example,lets declare an array

int x[5];

by doing that you are telling the compiler to allocate 5 available integer memory address.So you will get an allocated area and your size will be 5.
Lets assume the compiler gives you 5 address starting from 0x20000580--0x20000584
by writing

x[0] = data0;// you are writing data to  the address of 0x20000580-> data0             

x[1]= data1;// 0x20000581-> data1 

...

x[4]= data4 //0x20000584->data4

so in your case when you try to write x[size] which is x[5] you are trying to access
an un-allocated area and this cause hard fault
interrupt and you will face unhand-led exception.

Take a look at this line

printf("The maximal word lexicographically is: %sn", words[size]);

                                                      ^^^^^^^^^^^

the last valid element in an array is at index size-1 but you index the array using size. In other words - an out of bounds access.

So change to

printf("The maximal word lexicographically is: %sn", words[size - 1]);

                                                      ^^^^^^^^^^^^^^^

BTW:

This line

if (strcmp(strings[i], strings[i + 1]) >= 0) {

seems to open up for an endless loop in case two strings are identical. You probably don't want >= but only >