Rounding to Hundreths

This is a discussion on Rounding to Hundreths within the C++ Programming forums, part of the General Programming Boards category; I have a little program that calculates the bill of burgers, cokes, etc. but I want to round the tax ...

  1. #1
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    Question Rounding to Hundreths

    I have a little program that calculates the bill of burgers, cokes, etc. but I want to round the tax so that it doesn't go 4 places (only 2 like $).

    Now, that may be simple, but I would prefer that if there are any digits after the hundreths, it automatically goes up:

    $0.4109 --> $0.42

    Hope you can help.

    Thanks

  2. #2
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    Use the ceil function in math.h

    Code:
    #include <stdio.h>
    #include <math.h>
    
    int main ( ) {
        double p = 3.4109;
        p = ceil( p * 100 ) / 100;
        printf( "%.2f\n", p );
        return 0;
    }

  3. #3
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    I don't have the math.h library. Should I?

  4. #4
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    This being C++, maybe its called
    #include <cmath>

    If you have neither, you have a seriously broken compiler - it's supposed to be a standard feature.

  5. #5
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    OK, I found it. It's there, I just mistyped the #include before. But now that I found the math.h library, I need to initialize printf. Should I just do so and make it 0 at the top?

  6. #6
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    Error: implicit declaration of function 'int printf(...)'

    That subject line was the new error before I tried to initialize printf. I realize that it's a function, but it ain't workin

  7. #7
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    or use cout, since this is C++

  8. #8
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    Beautiful, man! How did you figure that out? I looked at that ceil function, but I still can't see how it's different than the others in the math.h library.

    Another side question: Can you use images for outputs like in BASIC? Basically, I want to line up the decimals so it doesn't look funny if the bill is $100, while the tax is $7.

    Thanks again

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