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Having "if statement" check input for integer.

This is a discussion on Having "if statement" check input for integer. within the C Programming forums, part of the General Programming Boards category; Ok, I have been looking online, but I can't find any help for my limited knowledge so far in my ...

  1. #1
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    Having "if statement" check input for integer.

    Ok, I have been looking online, but I can't find any help for my limited knowledge so far in my course.

    I am making a basic program that you input an integer for month and one for day. I have it set up already to give an error if it is beyond the limit of how many months their are and days in a month (exluding Feb special rules). The tricky part though is making the "if statements" verify that the input from the user isn't a decimal number.

    While looking online I could find solutions pertaining while loops and all these other commands I am not supposed to have learned yet, so I shouldn't use them. All I have at my disposale are basic arguments within if statements.

    My code so far:

    Code:
    #include <stdio.h>
    
    int main()
    {
    
    int month, day;
    
    printf("Enter a month (use a 1 for Jan, etc.): ");
    scanf("%d", &month);
    printf("Enter a day of the month: ");
    scanf("%d", &day);
    
    if (month < 1 || month > 12 || month%1 != 0)
        printf("Interger for month entered was %d and is an invalid entry", month);
    else if (day < 1 || day > 31 || day%1 != 0)
        printf("Interger for day entered was %d and is an invalid entry", day);
    else {
        printf("The month entered was %d and the day of the month %d", month, day);
    }
    return 0;
    }
    I was trying to use the modular command to check for a remainder, but when I run the program I am getting:

    [cameron@localhost Program4]$ make Exercise2
    cc Exercise2.c -o Exercise2 //No Errors from Compiler
    [cameron@localhost Program4]$ ./Exercise2
    Enter a month (use a 1 for Jan, etc.): 1
    Enter a day of the month: 2
    The month entered was 1 and the day of the month 2 //Normal run that works
    [cameron@localhost Program4]$ ./Exercise2
    Enter a month (use a 1 for Jan, etc.): 1.2 //Trying to input decimal number
    Enter a day of the month: Interger for day entered was 0 and is an invalid entry[cameron@localhost Program4]$ //Says Integer for day was 0 and shuts down.

  2. #2
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    Guess you guys don't know either. Oh well. Assignment is due in 30 min. Spent 1 1/2 hours on this part alone lol. Can't find anything on google search that doesn't involve while loops or something else that my book hasn't gone over yet.
    Last edited by Cameron Taylor; 06-12-2013 at 11:30 PM.

  3. #3
    and the hat of int overfl Salem's Avatar
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    > Guess you guys don't know either. Oh well. Assignment is due in 30 min.
    Well you only waited about 40 minutes before complaining. This is a forum with users from all around the planet, not some helpdesk with always available help.

    Enter a month (use a 1 for Jan, etc.): 1.2 //Trying to input decimal number
    Enter a day of the month: Interger for day entered was 0 and is an invalid entry[cameron@localhost Program4]$ //Says Integer for day was 0 and shuts down.
    scanf("%d", &month);
    printf("Enter a day of the month: ");
    scanf("%d", &day);

    Here's how it works.
    You type in "1.2\n"
    the first scanf removes 1, stopping at the . (it's not part of an integer).
    1 is assigned to month, and the return result is also 1 (which you DON'T check).

    The second scanf comes along, sees the . in ".2\n" left over from last time and immediately bails out.
    Nothing is assigned to day, and the return result of scanf is zero.
    King Mir likes this.
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