Printing Double?

This is a discussion on Printing Double? within the C++ Programming forums, part of the General Programming Boards category; I would like to know how to print double variable if it is assigned a number with alot of digits. ...

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    Printing Double?

    I would like to know how to print double variable if it is assigned a number with alot of digits.

    For example, if i were to cout<<(double)100000000<<endl i would get printed "1e+008" printed out. However, I would like to get "100000000" How would I accomplish this?

  2. #2
    C++まいる!Cをこわせ! Elysia's Avatar
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    Try
    std::cout << std::fixed << 100000000.0 << std::endl;
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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    Thanks. is there a way to limit the number of zeros to the needed length? like...

    double a = 5;
    cout<<fixed<<a<<endl;

    would print out something like...
    5.0000000000

    when simple 5 or 5.0 would be sufficient.

  4. #4
    C++まいる!Cをこわせ! Elysia's Avatar
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    Try std::setprecision.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  5. #5
    BMJ
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    cout.precision(1);
    cout << fixed << a << endl;

    e: I'm not quite fast enough

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    C++ unfortunately makes formatting a clumsy affair. In C++ a programmer uses tiny objects called manipulators to change the way the stream behaves. You can find the manipulators that C++ has standard in any reference page: C++ I/O Flags [C++ Reference]. It is important that you become familiar with these.

    You can also make your own manipulators.

    It is also nice to remove the format after you are done:

    cout.resetiosflags( ios_base::showpoint );

    Forgetting to do that can make output look strange sometimes when you don't expect it.

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    C++まいる!Cをこわせ! Elysia's Avatar
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    There is also Boost's Format library which tries to combine the best of both worlds: The Boost Format library
    Though I suck at using it (mainly because the documentation is so poor). I only use it for basic formatting.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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    Nvm...

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