Reading a character from the keyboard getchar()

This is a discussion on Reading a character from the keyboard getchar() within the C Programming forums, part of the General Programming Boards category; hello all In a do while I'm printing a menu, getting a character from the keyboard and run a switch ...

  1. #1
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    Reading a character from the keyboard getchar()

    hello all

    In a do while I'm printing a menu, getting a character from the keyboard and run a switch statement in the cases where that character is "d, v or f". the condition executes until the keystroke is 'e'.

    using the getchar() function I get my menu printed twice. What am I doing wrong?

    Code:
    char check;
    do {
           prinf("Menu:");
                   ...
           check = getchar();
           switch (check)
           {
                case 'f':
                
                case 'd':
     
                case 'v':
    
                default:
           }
         } while(check != 'e');

  2. #2
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    Well actually It prints once and then runs the default case and prints again.

  3. #3
    Programming Wraith GReaper's Avatar
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    Quote Originally Posted by mnml View Post
    Well actually It prints once and then runs the default case and prints again.
    This happens because the newline character is being fetched the second time. For what you want, you could use:
    scanf("%c\n", &check);
    "scanf()" performs pattern matching, so you could use it to your advantage.
    Devoted my life to programming...

  4. #4
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    With scanf() I need to press a character, Enter, and then another character which is the option from the menu to run the switch statement.

  5. #5
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    this is my complete do while condition


    Code:
    char menu;
    
     do {
            printf("MAIN MENU\n");
            printf("[d] Display Empty Chess Board\n");
            printf("[v] Check Validiti of Chess Notation\n");
            printf("[s] Save Moves to e Text File\n");
            printf("[e] End program\n");
            printf("Selection [d, v, s, f, e]: ");
            
            scanf("%c\n", &menu);
            
            if (menu != 'e')
            {
               switch(menu)
               {
                   case 'd':
                     display_board();
                     break;
                
                   case 'v':
                     check_move();
                     break;
                     
                   case 's':
                     save_move();
                     break;
                
                   default:
                     printf("wrong character. Print menu again\n\n");
                     break;
               } // switch
            } // if
         } while(menu != 'e');
    Now with scanf() thats what I get in the console the first time it executes:

    MAIN MENU
    [d] Display Empty Chess Board
    [v] Check Validiti of Chess Notation
    [s] Save Moves to e Text File
    [e] End program
    Selection [d, v, s, f, e]: d
    d

    Notice that I type "d - Enter - d" before the switch statement executes.

    then display_board() runs and the menu is printed again. Not only that but when I give 'v' after that, display_board() executes again and not the check_move() funtion
    Last edited by mnml; 10-21-2011 at 09:23 AM.

  6. #6
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    Try it this way...
    Code:
    scanf (" %c", &menu);
    Note the space between the first quote and the % sign... that tells it to ignore invisible characters.

  7. #7
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    Thanks

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