displaying data from a structure of arrays

This is a discussion on displaying data from a structure of arrays within the C Programming forums, part of the General Programming Boards category; the user has entered data, and i am wanting to print off specific parts of the data. The user is ...

  1. #1
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    displaying data from a structure of arrays

    the user has entered data, and i am wanting to print off specific parts of the data. The user is to enter a catagory, and all the videos in this catagory to be printed off. I cant figure out what is wrong with this code, can anyone help?

    printf("Enter the catagory of video you would like displayed (Kids,Action,Romance,Thriller) - ");
    fflush(stdin);
    scanf("%s", Selection);
    fflush(stdin);

    printf("\n\n");

    printf("Number Title Certificate Catagory Daily Rental Available\n\n");

    for (j = 0; j < i; j++)
    if (0 != (strstr(((VideoData[j].videotitle)[j])=VideoData[j].videotitle, Selection)))
    {
    PrintOne((VideoData[j].videotitle)[j]);
    }

    printf("\n\nTo return to the main menu press any key ");
    getch();

  2. #2
    Code Goddess Prelude's Avatar
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    >printf("Enter the catagory of video you would like displayed(Kids,Action,Romance,Thriller) - ");
    >fflush(stdin);
    >scanf("%s", Selection);
    >fflush(stdin);
    This is really not a good idea. Using fflush on input streams results in undefined behavior. If you want to get rid of floating characters after calls to scanf replace fflush ( stdin ); with

    while ( getchar() != '\n' );

    every time you use scanf to read string data. You could avoid this problem altogether by using fgets when reading string data and scanf only when reading numeric data.

    >if (0 != (strstr(((VideoData[j].videotitle)[j])=VideoData[j].videotitle, Selection)))
    This is just plain ugly, if your structure is formatted with any sanity at all then you should simply be able to do something like this:
    Code:
    /* Add an enum to make the mode easier to understand 
    */
    enum {CATEGORY, TITLE, and so on };
    
    /* Use a switch to dermine how to test the struct 
    */
    switch ( modeSelection ) {
    case CATEGORY:
      if ( strcmp ( VideoData[j].category, Selection ) == 0 )
        PrintOne ( VideoData[j], modeSelection );
      break;
    .
    .
    }
    
    /* The definition of PrintOne would look something like this.
    ** Using another switch to determine what to print. 
    */
    void PrintOne ( struct Video *vid, int mode )
    {
      switch ( mode ) {
      case CATEGORY:
        /* Print the category details */
      case TITLE:
        /* Print the title details */
      .
      .
      }
    }
    -Prelude
    My best code is written with the delete key.

  3. #3
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    okay, i've changed a bit, but this still sint working. it accepts the user input of a catagory, but it doesnt seem to look through the array to find any videos with that catagory. any ideas?

    printf("Enter the catagory of video you would like displayed (Kids,Action,Romance,Thriller) - ");
    scanf("%s", UserCat);

    printf("\nSearching for \"%s\"...\n", UserCat);

    printf("\n\n");

    printf("Number Title Certificate Catagory Daily Rental Available\n\n");

    for (j = 0; j < i; j++)
    if ( strcmp ( VideoData[j].videotitle, UserCat ) == 0 )
    {
    printf("%-9.9s %-16.16s %-12.2s %-10s %-14.2f %c\n", VideoData[j].videonumber, VideoData[j].videotitle, VideoData[j].videocert, VideoData[j].videocat, VideoData[j].dailyrental, VideoData[j].available);
    }
    else
    {
    printf("Sorry we have no videos in that catagory available");
    }

  4. #4
    Code Goddess Prelude's Avatar
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    I may be wrong and you have unusual naming conventions, but
    if ( strcmp ( VideoData[j].videotitle, UserCat ) == 0 )
    should be
    if ( strcmp ( VideoData[j].category, UserCat ) == 0 )

    If you plan to check all of the videos by category then it might be a good idea to test the user input ( which is a category ) with the category member of the struct. Otherwise the search probably won't find anything worthwhile.

    -Prelude
    My best code is written with the delete key.

  5. #5
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    thanks! i got it!

  6. #6
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    i also now want to check that the video is available and has not been rented out allready. The bit of code ive added doesnt seem to be working. Any ideas?for (j = 0; j < i; j++)
    if ( VideoData[j].available == "Y" &&
    strcmp ( VideoData[j].videocat, UserCat ) == 0 )
    {
    printf("%-9.9s %-16.16s %-12.2s %-10s %-14.2f %c\n", VideoData[j].videonumber, VideoData[j].videotitle, VideoData[j].videocert, VideoData[j].videocat, VideoData[j].dailyrental, VideoData[j].available);
    }

  7. #7
    Code Goddess Prelude's Avatar
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    >if ( VideoData[j].available == "Y" &&
    If the user won't be looking at the available option, you can declare it as int and use 0 and 1 to determine availability. Otherwise if it's already declared as a char use 'Y' in your test and make sure that when you change the availability you use upper case letters.

    -Prelude
    My best code is written with the delete key.

  8. #8
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    its not working, cant see why. Its only stopped working since i added "VideoData[j].available == "Y" &&" to it.

    for (j = 0; j < i; j++)
    if (VideoData[j].available == "Y" && strcmp (VideoData[j].videocat, UserCat) == 0)
    {
    printf("%-9.9s %-16.16s %-12.2s %-10s %-14.2f %c\n", VideoData[j].videonumber, VideoData[j].videotitle, VideoData[j].videocert, VideoData[j].videocat, VideoData[j].dailyrental, VideoData[j].available);
    }

  9. #9
    Code Goddess Prelude's Avatar
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    First, make sure that your struct actually has a member called available. Then if it's a char, use this
    if (VideoData[j].available == 'Y' && strcmp (VideoData[j].videocat, UserCat) == 0)

    Then check to see that you set the variable at some point. If you don't set available videos to 'Y' then the chance of a random value being what you want is slim.

    -Prelude
    My best code is written with the delete key.

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