Do While error prints twice despite scanf

I am trying to teach myself C and decided to make a console project that would be a Basal Metabolic Weight/BMI/Calorie Calculator. Anyways I am stumped early on with this problem. Can anyone tell me where I went wrong? I have been racking my brain but haven't been able to figure it out. (But I am somewhat new at this) Thanks!!!

Melissa

Code:

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#include <stdio.h>

int main()
{
    char Gender = 'a';
    char tempGender;

    //Title
    printf("WEIGHT LOSS CALCULATOR \n\n\n");
    //Gather gender info
    do {
        printf("Are you male or female? \nType M for male and F for female.\n\n");
        scanf("%c", &tempGender);
        //printf("%c",tempGender\n);

        if (tempGender == 'm' || tempGender == 'M') {
            Gender = 'm';
            printf("You are a male.\n\n");
        }
        else if (tempGender == 'f'|| tempGender == 'F') {
            Gender = 'f';
            printf("You are a female.\n\n");
        }
        else {
            printf("ERROR. Please try again.\n\n");
            printf("You typed: %c\n",tempGender);

        }
        }while (Gender == 'a');
return 0;
}

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Code:

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scanf("%c", &tempGender);

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Instead try this; the leading space means skip space like the newline.

Code:

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scanf(" %c", &tempGender);

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Tim S.

Thanks! That worked! Should I always put that space? Really Thank you :)

Melissa

Quote:

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Originally Posted by mreneeholland

Should I always put that space?

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No. Putting the space is an (ugly) workaround about the misuse of the scanf() function.
What you should do is understand why the space works, and what are the better alternatives.

1) scanf() was designed to work with formatted data (and it has very limited error validation/checking/recovery).
2) User input has no resemblance at all to formatted data
3) scanf() and user input are mostly incompatible
4) prefer to use fgets() to get a full line from the user
5) parse that line with, for example, sscanf().
6) ignore the fact your program is a few lines longer: it is also very many times more solid.

Thank you for taking the time to explain this to me. I will definitely run through more tutorials and try to get a better understanding between the different syntax options and uses. I have only done a little Visual Basic at a beginner level. Thank you again :)

You can also do this

Code:

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scanf("%c%*c",  &tempGender);

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The %*c reads the new line character (left over from when you hit enter) and then does nothing with it (basically so it is not left on the input).

scanf returns the number of successful inputs - So you can monitor if your user was successful in inputting a number.

Using fgets and then sscanf is a long way of doing the same thing - I don't think that it's necessary.