calender problem

**roelof** · 06-06-2011

hello,

I have to make a calender in C.
The user has to enter the number of days in that monts and which day the month starts.
So I made this :

Code:

/*
 * =====================================================================================
 *
 *       Filename:  test.c
 *
 *    Description:  test
 *
 *        Version:  1.0
 *        Created:  05-06-11 21:07:38
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Dr. Fritz Mehner (mn), [email protected]
 *        Company:  FH Südwestfalen, Iserlohn
 *
 * =====================================================================================
 */


#include        <stdio.h>
        int
main ( int argc, char *argv[] )
{

        int begin , dagen, teller, teller2, uitkomst ;
        begin = 0;
        printf ("Hoeveel dagen in een maand : ");
        scanf ("%d", &dagen);
        printf ("Op welke dag moet de maand starten (0 = Zondag, 7 = Zaterdag)");
        scanf ("%d", &begin);
        for (teller=1; teller <=dagen; teller++);
                {
                        for (teller2=1 ; teller2 <=begin-1; teller2++)
                                {
                                        printf ("\t");
                                }
                        printf ("%d", teller);
                        if (teller > 7)
                                {
                                        begin = 0 ;
                                }
                        uitkomst = (teller + begin)%7 ;
                        if (uitkomst == 0)
                                {
                                        printf ("\n");
                                }

                }
        return 0;
}                               /* ----------  cnd of function main  ---------- */

But now the only output I see is the number the user enters +1

What am I doing wrong ?

Roelof

**Salem** · 06-06-2011

> for (teller=1; teller <=dagen; teller++);
The ; at the end of this line.

**roelof** · 06-06-2011

Thanks.

Now I can try to solve the other problems.

Roelof

**roelof** · 06-06-2011

Hello,

Another thing I don't get.
I have now this :

Code:


#include        <stdio.h>
        int
main ( int argc, char *argv[] )
{

        int begin , dagen, teller ;
        float  uitkomst ;
        begin = 0;
        uitkomst= 0 ;
        printf ("Hoeveel dagen in een maand : ");
        scanf ("%d", &dagen);
        printf ("Op welke dag moet de maand starten (0 = Zondag, 7 = Zaterdag)");
        scanf ("%d", &begin);
        for (teller=1; teller <=begin; teller++)
        {
                printf ("\t");
        }
        for (teller=1; teller <=dagen; teller++)
                {
                        if (teller > 7)
                                {
                                        begin = 0 ;
                                }
                        uitkomst = (teller + begin)%7 ;
                        printf ("uitkomst : %f", uitkomst);
                        printf ("%d \t", teller);
                        if (uitkomst == 0)
                                {
                                        printf ("\n");
                                }

                }
        return 0;

What I don't get it this :

I have this uitkomst = (teller + begin) %7 so I can see if it can be divide by 7.
Let's say teller = 1 and uitkomst =1 then it would be (1+1)%7 is 2/7 = 0.28
But according to the print rule the outcome = 1.000007

Can someone explain me why ?

Roelof

**Salem** · 06-06-2011

printf ("uitkomst : %f", uitkomst);
printf ("%d \t", teller);
The first line prints 1.00000
The second line prints 7

Since there is no space between them, it looks like one number.

**roelof** · 06-06-2011

Oke,

I have changed it and now getting this output:

Code:

	uitkomst : 2.000000 
1 	uitkomst : 3.000000 
2 	uitkomst : 4.000000 
3 	uitkomst : 5.000000 
4 	uitkomst : 6.000000 
5 	uitkomst : 0.000000 
6 	
uitkomst : 1.000000 
7 	uitkomst : 1.000000 
8 	uitkomst : 2.000000 
9 	uitkomst : 3.000000 
10 	uitkomst : 4.000000 
11 	uitkomst : 5.000000 
12 	uitkomst : 6.000000 
13 	uitkomst : 0.000000 
14 	
uitkomst : 1.000000 
15 	uitkomst : 2.000000 
16 	uitkomst : 3.000000 
17 	uitkomst : 4.000000 
18 	uitkomst : 5.000000 
19 	uitkomst : 6.000000 
20 	uitkomst : 0.000000 
21 	
uitkomst : 1.000000 
22 	uitkomst : 2.000000 
23 	uitkomst : 3.000000 
24 	uitkomst : 4.000000 
25 	uitkomst : 5.000000 
26 	uitkomst : 6.000000 
27 	uitkomst : 0.000000 
28 	
uitkomst : 1.000000 
29 	uitkomst : 2.000000 
30 	uitkomst : 3.000000

The outcome still is not right. 1/7 is .14 and not 3 as the output of my programm is.

Roelof

**mike65535** · 06-06-2011

Code:

printf ("uitkomst : %f", uitkomst);

prints uitkomst which is given by:

Code:

uitkomst = (teller + begin)%7

which is the remainder of (teller + begin) / 7
which is always essentially an integer, hence the 1.00000, 2.00000 print statements. (Why do those not cause you concern?)

**roelof** · 06-06-2011

I only have to know if the outcome will be 0 because then I need to do a newline.
The other numbers are not important

Roelof

**mike65535** · 06-06-2011

What do you mean by:

The outcome still is not right. 1/7 is .14

Apparently you *do* care what it is since this is troubling you.

Can you debug and watch what happens to your variables as you go through the loops?

**roelof** · 06-06-2011

Hello,

When I know how to do that in vim I can do that.

Roelof

**mike65535** · 06-06-2011

I hinted to you before about modulus operation. Do you understand that the remainder is really an integer value, and NOT a float?

**roelof** · 06-06-2011

I understand that

Roelof

**mike65535** · 06-06-2011

This looks suspicious:

Code:

        if (teller > 7) {
            begin = 0 ;
        }

You realize that begin will be reset to zero for all values of teller greater than 7? Not sure what you are doing with this...

**mike65535** · 06-06-2011

Originally Posted by roelof

I understand that

Roelof

Then why would you expect 0.14 as an output?

**mike65535** · 06-06-2011

Code:

printf ("Op welke dag moet de maand starten (0 = Zondag, 7 = Zaterdag)");

Saturday cannot be day '7' if Sunday is day '0'

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