a problem

This is a discussion on a problem within the C Programming forums, part of the General Programming Boards category; hi i'm a newbie to c and am trying to create a program that calculates the "greatest common divisor". i'm ...

  1. #1
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    a problem

    hi i'm a newbie to c and am trying to create a program that calculates the "greatest common divisor". i'm always getting 0 as the result. here's my src:
    Code:
     #include <stdio.h>
    
    main() {
       int m, n, i;
       
       printf("Enter two integers: ");
       scanf("%d%d", &m, &n);
       do {
          i = m / n;
          n = m % n;
          m = i;
       } while ( n != 0 ) ;
       printf("Greatest common diviser: %d", m);
       return 0;
    }
    i would be grateful if someone can help me. btw i'm using Devcpp.

  2. #2
    Frequently Quite Prolix dwks's Avatar
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    I think there's something wrong with your formula.
    dwk

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  3. #3
    The Richness... Richie T's Avatar
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    I normally try not to give away the whole answer, but this pretty much sums it
    up very neatly, so I thought I'd be nice and post it. Take the pseudocode
    shown here and convert it to actual code, and that's it.

    EDIT: main returns int, see my sig
    Last edited by Richie T; 09-03-2006 at 12:10 PM.
    No No's:
    fflush (stdin); gets (); void main ();


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    thanks alot yes there was a problem in my formula. this is my new src:
    Code:
     #include <stdio.h>
    
    main() {
       int m, n, i;
       
       printf("Enter two integers: ");
       scanf("%d%d", &m, &n);
       do {
          i = n;
          n = m % n;
          m = i;
       } while ( n != 0 ) ;
       printf("Greatest common diviser: %d", m);
       return 0;
    }
    thanks alot guys. i don't know i'v been working on it for an hour yesterday and couln't get it, today i fixed it within 15 min. anyways i'm also trying to make a program that ask the user to enter a number, then reverse it's digits. i know how to do it with a limited number of digits, but how can i do it with an almost unlimited(as the int type doesn't support all numbers) number of digits.
    thanks again.

  5. #5
    The Richness... Richie T's Avatar
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    Read the data into a string and print it in reverse.
    No No's:
    fflush (stdin); gets (); void main ();


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  6. #6
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    i didn't learn about strings yet all i know is the basics(ex. loops, if statement).

  7. #7
    The Richness... Richie T's Avatar
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    Well we'll use int then:

    1. Read in a number
    2. print number % 10
    3. divide number by 10 and save result in number (variable name in this context)
    4. repeat steps 2 and 3 while number is not 0.

    That should do it for any int value.
    No No's:
    fflush (stdin); gets (); void main ();


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    Example of fgets (); The FAQ, C/C++ Reference


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    thanks richie it worked
    Last edited by Abda92; 09-03-2006 at 12:49 PM.

  9. #9
    Registered User ssharish2005's Avatar
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    it is good practice to specify the int before the main, even thought is dosn't matter as the compiler would assume it as an int. So change it to
    Code:
    int main()
    {
       ...
       ...
       return 0;
    }
    to follow the good programming practice

    ssharish2005

  10. #10
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    what's the difference between "main()" and "int main"?

  11. #11
    The superhaterodyne twomers's Avatar
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    int main() is right ... or int main( void ) is right http://faq.cprogramming.com/cgi-bin/...&id=1043284376

  12. #12
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    whats a "boolean"?
    Last edited by Abda92; 09-04-2006 at 08:49 AM.

  13. #13
    Register User andor's Avatar
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    It's a type which vars can be only one or zero.
    Code:
    typedef enum 
    {
      FALSE = 0,
      TRUE
    } MY_BOOL;
    Last edited by andor; 09-04-2006 at 07:35 AM.

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    thanks guys i'm sorry but i'm having some trouble. i'm trying to write a program that prints a one-month calendar, the user specifies the number of days in the month and the day of wich the month begins. here's my src:
    Code:
    #include <stdio.h>
    main() {
       int i, n, j;
       
       printf("Enter number of days in month: ");
       scanf("%d", &n);
       printf("Enter starting day of the week (1=Sun, 7=Sat): ");
       scanf("%d", &j);
       for (i = 1; i <= n; i++) {
          printf("j = %d", j);
          j++;
          if (j > 7) {
             printf("\n");
             j = 1;
          }
       }
       return 0;
    }
    i'm sorry i have two probs:1) i don't know how to make the the month begin on a specific day(ex. the month begins on thursday). 2) i don't know how to make the program start a new line. i think this problem is because of the first prob.
    thanks

  15. #15
    and the hat of wrongness Salem's Avatar
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    > for (i = 1; i <= n; i++)
    Before you do this, you need a loop involving 'j' to work out how far to indent the first line.

    > printf("j = %d", j);
    Print i, which contains the day number.
    To make the formatting look nicer, try
    printf( "%2d ", i );
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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