Try again decision problem

This is a discussion on Try again decision problem within the C Programming forums, part of the General Programming Boards category; Hi guys! can you help a novice programmer here. I've been working on a Try again decision using the Do-While ...

  1. #1
    Registered User hawkeye10's Avatar
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    Try again decision problem

    Hi guys! can you help a novice programmer here. I've been working on a Try again decision using the Do-While loop. Heres the code I've established.

    Code:
    #include <stdio.h>
    
    int main(void)
    
    {
    
    
    // Declaration of Variables
    double Pounds = 0;
    double Kilograms = 0;
    double Inches = 0;
    double Meters = 0;
    double BMI = 0;
    
    char ans1 = ' ';
    char ans2 = ' ';
    char ans3 = ' ';
    
    
        do
        {
            {
            printf("Please enter your height(Meters): ");
            scanf("%lf", &Meters);
                
            printf("Please enter your weight(Kilograms): ");
            scanf("%lf", &Kilograms);
                
            BMI = Kilograms/(Meters*Meters);
                
            printf("Your BMI (Meters&Kilograms) is: %.2f\n", BMI);
            }
        
        printf("Would you like to try again? (y/n): ");
        scanf("%c", &ans1);
        fflush(stdin);
        }
        while (ans1 =='y');
        
    }
    
    The whole thing works until I reach the try again decision.

    Code:
    Please enter your height(Meters): 
    1.6
    Please enter your weight(Kilograms): 
    52
    Your BMI (Inches&Pounds) is: 20.31
    Would you like to try again? (y/n): 
    Program ended with exit code: 0
    This is what I always end up with. I would really appreciate the help

  2. #2
    DRK
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    Call fflush(stdin) before every scanf()

  3. #3
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    Quote Originally Posted by DRK View Post
    Call fflush(stdin) before every scanf()
    No! Never call fflush(stdin). Read this link: FAQ > Why fflush(stdin) is wrong - Cprogramming.com.

    @OP:
    Note, when you hit enter, like you do after entering your height/weith, that puts a new line ('\n') in the input buffer. scanf, when used with the %c, doesn't skip leading white space like the other modifiers (%d, %lf, etc) do. That means when you scan a char into ans1, you scan in the '\n'. You can force scanf to skip any leading whitespace, including '\n', by putting a space before the %c, like scanf(" %c", &ans1).

  4. #4
    DRK
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    Sorry, my advice wasn't correct, I was sugested by fflush(stdin) already used in the example code.

  5. #5
    Registered User hawkeye10's Avatar
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    Quote Originally Posted by anduril462 View Post
    No! Never call fflush(stdin). Read this link: FAQ > Why fflush(stdin) is wrong - Cprogramming.com.

    @OP:
    Note, when you hit enter, like you do after entering your height/weith, that puts a new line ('\n') in the input buffer. scanf, when used with the %c, doesn't skip leading white space like the other modifiers (%d, %lf, etc) do. That means when you scan a char into ans1, you scan in the '\n'. You can force scanf to skip any leading whitespace, including '\n', by putting a space before the %c, like scanf(" %c", &ans1).
    Got it! Thanks for the help dude!

    Code:
    Please enter your height(Meters): 1.62
    Please enter your weight(Kilograms): 59
    Your BMI (Inches&Pounds) is: 22.48
    Would you like to try again? (y/n): y
    Please enter your height(Meters): 
    

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