Question

What is the error in my program? This is the code:

/*
 * courseProject.c
 *
 * It is a simple database for record shop
 * to track its iventory of CDs
 *
 * by Mahmoud Emam, 2012.
 */
#include<stdio.h>

main()
{
      /*
       * CDs infrormations
       */
      char title[31], artist[31];
      short int numberOfTracks;  /* short to save memory */
      int albumOrSingle;         /* Boolean to check 1 for Album and 0 for Single */
      float price;

      printf("Hello, Welcome to Record Shop!\n\n");
      /*
       * Asking for CD details
       */
      printf("Enter CD details\n\n");
      printf("CD's Title: ");
      scanf("%[^\n]", title);
      fflush(stdin);

      printf("CD's Artist: ");
      scanf("%[^\n]", artist);


      printf("Number of tracks: ");
      scanf("%d", &numberOfTracks);


      printf("Please press \"1\" for album, \"0\" for single: ");
      scanf("%d", &albumOrSingle);


      printf("CD's Price: ");
      scanf("%f", &price);

      /*
       * Output CD details
       */
      printf("\nCD details:\n");
      printf("=============\n\n");

      printf("CD's Title: <%s>\n", title);
      printf("CD's Artist: <%s>\n", artist);
      printf("Number of tracks: <%d>\n", numberOfTracks);

      if (albumOrSingle)
         printf("This is <Album>\n");
      else
         printf("This is <Single CD>\n");

      printf("Its price = <%.2f>\n", price);
      printf("=============\n\n");

      /* Exit from program */
      printf("Press any key to exit\n");

      fflush(stdin);
      getchar();
}

This is a simple program that reads CD info from the user and outputs the details again on the screen. However, the artist variable is always empty. Why?

I made printf("%s", artist); after I read it from the user and it works correctly, but it doesn’t work at the end of the program. The variable is always empty.

Answer 1

The variable numberOfTracks is a short int, but you are reading it with scanf‘s %d specifier, which reads an int. This leads to undefined behavior – in this case it probably overwrites other variables such as artist.

Either use the %hd specifier (which reads a short int), or change the variable to an int.