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How do I delimit a single character with scanf?

This is a discussion on How do I delimit a single character with scanf? within the C Programming forums, part of the General Programming Boards category; Code: #include <stdio.h> int main{ char move; scanf ("%c",&move"); switch (move) case w: {y-move +=1; movechar();break;} case a: {x-move -=1; ...

  1. #1
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    How do I delimit a single character with scanf?

    Code:
    #include <stdio.h>
    int main{
    char move;
    scanf ("%c",&move");
    switch (move)
    case w: {y-move +=1; movechar();break;}
    case a: {x-move -=1; movechar();break;}
    case s: {y-move -=1; movechar();break;}
    case d: {x-move +=1; movechar();break;}
    return 0;
    }
    Sorry, it's my first time here as a member but i've been using this site to selfteach C programming. Not sure if I posted the thread right but if I did make a mistake to the post please correct me.

    Im making a small game where it requires movement of a piece with (w,a,s,d) keys.
    I've read about delimiters in strings, where you can use it to stop scanning when a certain key is pressed.

    here's my question.
    how do I do that same operation with the line 4(scanf): if w,a,s, or d is pressed immediately enter the following key. (without physically pressing enter everytime. the key is immediately registered and moves on to the next line)
    Last edited by alex3064; 11-29-2012 at 08:47 PM.

  2. #2
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    Try using getchar() instead of scanf

  3. #3
    and the hat of wrongness Salem's Avatar
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    > (without physically pressing enter everytime. the key is immediately registered and moves on to the next line)
    Non-blocking input is very specific to your OS/Compiler.
    FAQ > How can I get input without having the user hit [Enter]? - Cprogramming.com
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  4. #4
    TEIAM - problem solved
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    Does your compiler have the header conio.h?

    If so, use the getch function from it.
    Fact - Beethoven wrote his first symphony in C

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    Quote Originally Posted by Salem View Post
    > (without physically pressing enter everytime. the key is immediately registered and moves on to the next line)
    Non-blocking input is very specific to your OS/Compiler.
    FAQ > How can I get input without having the user hit [Enter]? - Cprogramming.com
    Ah thanks for the link. Did not find that faq i guess i was searching incorrectly.
    So with scanf, Its impossible. Ill try with getch

  6. #6
    Stoned Witch Barney McGrew's Avatar
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    I can see a few errors with the code you've posted.
    - Your definition for main lacks a parameter list.
    - You have a double quote after the '&move' expression.
    - Unless w, a, s, and d are #defined or members of an enum, you're not using a constant for each case statement.
    - You're using the '-' character for the identifiers x-move and y-move.

    Another thing you might look out for is declaring identifiers with file scope. In most cases it's better to design 'movechar' so that it uses a list of parameters instead of file-scoped variables.

    As for receiving unbuffered input from a terminal, you could try reading the documentation for your terminal. I suggest writing programs that work well regardless of what stdin device stdin is connected to. If you need to write interactive programs, you might consider using a library like SDL or *curses, although it's usually better to get a good grasp of standard C before learning to use such libraries.
    laserlight and tost like this.

  7. #7
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    It might also be worth mentioning ncurses, you can read chapter 7 of the tutorial: Input functions

    So in your program, you could do something like:


    #include <ncurses.h>


    initscr();
    cbreak();


    ^to initialize, and once it's initialized, to read a character you can run:


    int ch; ch = getch();


    nCurses is one of my favorite libraries.
    Last edited by Andrew Thompson; 11-30-2012 at 01:07 AM. Reason: bad typos

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