Thread: Regex or scanf()?

  1. #1
    Registered User
    Join Date
    May 2004

    Regex or scanf()?

    Hi, I'm making a console-based connect four game as a beginner project, I want have the user input a command in this syntax, "drop <int column_number>" to drop a coin. The problem is how! I want to be able to seperate the number from the command a store it into a seperate variable - and if the syntax is not as expect, I do not want the program to crash, I want it to just ask again.

    I have tried something like below, which kind of works and then crashes straight after. My understanding of scanf() is limited because I do not have the MSDN library.
    PHP Code:
    int col;
    scanf("drop %d", &col);
    My understanding is that where %d is, is the value that will be put into col - please correct me if I am wrong.
    Last edited by Avochelm; 05-08-2004 at 11:02 PM.

  2. #2
    Software Developer jverkoey's Avatar
    Join Date
    Feb 2003
    University of Waterloo
    what might be better is to use scanf("%s",buff); and read a string in. Then use sscanf to parse the string afterwards. sscanf is basically the same as scanf, except it does it with constant strings and doesn't get the data as input from the user.

  3. #3
    Registered User
    Join Date
    May 2004
    If I do it like that, it essentially is still the same as getting the information from the user?

  4. #4
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    > My understanding of scanf() is limited because I do not have the MSDN library.
    Without a decent reference, any new function you come across will leave you guessing.
    Didn't something come with your compiler?

    As mentioned already (partly at least), use sscanf() to pull the input apart.
    #include <stdio.h>
    int main ( ) {
        char buff[BUFSIZ];
        while ( fgets( buff, BUFSIZ, stdin ) != NULL ) {
            int drop;
            if ( sscanf( buff, "drop %d", &drop ) == 1 ) {
                printf( "You dropped item %d\n", drop );
            } else {
                printf( "I don't understand %s", buff );
        return 0;
    Simply add more else if constructs to match all your other commands.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  5. #5
    mustang benny bennyandthejets's Avatar
    Join Date
    Jul 2002
    My understanding of scanf() is limited because I do not have the MSDN library.

    EDIT: Of course, it's impossible to find anything using the search feature at MSDN. Go to google and do it like this:

    " scanf"

    That will find what you need.
    Microsoft Visual Studio .NET 2003 Enterprise Architect
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  6. #6
    Registered User
    Join Date
    May 2004
    Thanks, I'm messing with the code =D I don't understand some it, off course, but it works perfectly and I can always find out the details later.

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