Need some help 1-month calendar almost working

Hello, I am new to C, and I need to create a calendar, where the user inputs the days of the month and what day the calendar starts on, such as Mo, Tu, we, etc, and show a calendar. I have the calendar output the correct number of days with formatting, but do not know how to start on a specific day? I am wondering how to turn the string of characters (we, th) into a number 1-7, I am thinking that would be the solution. Also, I need to show an error message if the starting day is not correct (ex. tg, mi). Here is my code:

as you can see I have certain parts taken out as a comment, because it did not work.

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <math.h>


int
main()
{
    int num_days;
    int i;
    char day;
    char day2;
    printf("This prigram displays the calender for a month.\n\n\n");
    printf("Enter number of days in month: \n");
    scanf("%i", &num_days);
    printf("Enter starting day of the week (Su,Mo,Tu,...,Sa): \n");
    scanf("%*[ \n]%c", &day);
    //if (day != "Su" || day != "Mo" || day != "Tu" || day != "We" || day != "Th" || day != "Fr" || day != "Sa" || day != "su" || day != "mo" || day != "tu" || day != "we" || day != "th" || day != "fr" || day != "sa")
      //  printf("That is an invalid day of the week.");
    //else {
    day2 = toupper(day);
    printf("%c\n", day2);
    //}
    printf("  Su  Mo  Tu  We  Th  Fr  Sa\n");


    for (i = 1 ;  i < num_days + 1 ;  ++i ){
        printf("%3i ", i);
    if(i % 7  ==  0)
        printf("\n");
    }
    printf("\n");


}

---

Here is my latest attempt, which still does not work:

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <math.h>


int
main()
{
    int num_days;
    char day;
    char day2;
    char Su, su;
    char Mo, mo;
    char Tu, tu;
    char We, we;
    char Th, th;
    char Fr, fr;
    char Sa, sa;


    printf("This program displays the calender for a month.\n\n\n");
    printf("Enter number of days in month: \n");
    scanf("%i", &num_days);


    printf("Enter starting day of the week (Su,Mo,Tu,...,Sa): \n");
    scanf("%*[ \n]%c", &day);


    day2 = toupper(day);


    printf("%c\n", day2);
    printf("  Su  Mo  Tu  We  Th  Fr  Sa\n");


    if (day == Su || day == su)
        printf("");
    else if (day == Mo || day == mo)
        printf("  ");
    else if (day == Tu || day == tu)
        printf("    ");
    else if (day == We || day == we)
        printf("      ");
    else if (day == Th || day == th)
        printf("        ");
    else if (day == Fr || day == fr)
        printf("          ");
    else if (day == Sa || day == sa)
        printf("            ");
    int count;
        for (count = 1 ;  count < num_days + 1 ;  count++ ){
        printf("%3d ", count);
    if(count % 7  ==  0)
        printf("\n");
        }
}

---

Thanks for the help!!!:)

One thing, int needs to be on the same line as main, ex int main() also you have char day but you are comparing it to 2 characters. you need to either change day to a string or change your days to T, M ,W H, F... ect that way it will be one character.

Actually there is nothing wrong with the int being on a separate line from the main(), C does not care. Any of the following are acceptable:

Code:

---

int main(void) // The most used version with no arguments.
int
main(void)  // Used by several Documentation systems to make locating the function names easier.
int
main
(void)  // Rarely used but legal C.

---

Second the following:

Code:

---

char Su, su;

---

Is creating two char variables one named Su, the other name su. These variables can hold only one character. You are however using these variables improperly. You never initialize these variables to any value before you try to compare them to your user input.

Also your variable day can also only hold one character. As stated by camel-man, you should be using C-strings or only ask for a single character input.

Jim

Ok thanks, I changed everything to S, M, T, etc, but I am still not seeing any progress, could you please show a sample code of what I should change with respect to starting on a certain day?

What I've done is assign day variables, with values - similar to what you were thinking about, above. Sun = 0, Mon = 1, Tue = 2, etc.

Then before the first day, do a bit of arithmetic to get the correct starting place:

Month starts on Tuesday, so blanks to be printed before the first day equals 2 * width of each day, in chars.

A bit simplistic, but it works fine.