Step by Step solution about How to resolve the algorithm Order by pair comparisons step by step in the C programming language

This C program demonstrates an interactive sorting algorithm that sorts an array of strings based on user input. Here's a detailed explanation:

• Header Files:

  • stdio.h, string.h, and stdlib.h are included for standard input/output, string manipulation, and memory allocation functions.

• interactiveCompare Function:

  • This function is the comparison function used by qsort. It takes two arguments, x1 and x2, which are pointers to string pointers.
  • It first casts these pointers to declare s1 and s2 as pointers to strings.
  • It keeps a static variable count to track the number of comparisons made.
  • It prints a prompt asking the user to compare s1 and s2 and input -1, 0, or 1 to indicate if s1 is less than, equal to, or greater than s2, respectively.
  • It stores the user's response in the response variable.
  • Finally, it returns the user's response, which will be used by qsort to determine the sorting order.

• printOrder Function:

  • This function is used to print the sorted order of the strings.
  • It prints an opening curly brace, iterates through the array of strings, printing each string separated by a space, and then prints a closing curly brace.

• main Function:

  • An array of strings items is initialized with the names of different colors.
  • sizeof(items)/sizeof(*items) calculates the number of elements in the array.
  • qsort is called to sort the array of strings. It takes the array, the number of elements, the size of each element, and the comparison function interactiveCompare.
  • After sorting, printOrder is called to print the sorted order of the strings.

• Execution:

  • When the program runs, it asks the user to compare pairs of strings interactively and provide input.
  • The interactiveCompare function is used to compare the strings based on the user's input.
  • The sorted order of the strings is printed according to the user's comparisons.

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

int interactiveCompare(const void *x1, const void *x2)
{
  const char *s1 = *(const char * const *)x1;
  const char *s2 = *(const char * const *)x2;
  static int count = 0;
  printf("(%d) Is %s <, ==, or > %s? Answer -1, 0, or 1: ", ++count, s1, s2);
  int response;
  scanf("%d", &response);
  return response;
}

void printOrder(const char *items[], int len)
{
  printf("{ ");
  for (int i = 0; i < len; ++i) printf("%s ", items[i]);
  printf("}\n");
}

int main(void)
{
  const char *items[] =
    {
      "violet", "red", "green", "indigo", "blue", "yellow", "orange"
    };

  qsort(items, sizeof(items)/sizeof(*items), sizeof(*items), interactiveCompare);
  printOrder(items, sizeof(items)/sizeof(*items));
  return 0;
}