need help with .clear()

This is a discussion on need help with .clear() within the C++ Programming forums, part of the General Programming Boards category; hi i dont know how and why use the .clear() function ie: Code: file.clear();//if file is a fstream or cin.clear();//working ...

  1. #1
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    need help with .clear()

    hi i dont know how and why use the .clear() function
    ie:

    Code:
    file.clear();//if file is a fstream or
    cin.clear();//working with cin
    please any help about the when and why to use it?

    thanks for any help

  2. #2
    Sweet
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    you'd want to use it if you know there is garabage in you streams eg.
    someone inputs a letter instead of a number.
    Woop?

  3. #3
    unleashed alphaoide's Avatar
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    http://cplusplus.com/ref/iostream/ios/clear.html

    I use it the most when I read EOF yet need to loop back and read again. At that point i have to call clear() that will allow me to read, otherwise it won't.
    source: compsci textbooks, cboard.cprogramming.com, world wide web, common sense

  4. #4
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    ok thanks for reply

  5. #5
    Registered User major_small's Avatar
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    expanding on what alphaoide said... it resets (clears) all the flags that have been set for that stream. for example, to set cout to only display two decimal points on floats:

    Code:
    cout.setf(ios::fixed);
    cout.setf(ios::showpoint);
    cout<<setprecision(2);
    and if you wrote
    Code:
    cout.clear()
    it would clear all the flags you just set.

    note: code not tested... I haven't used it in a long time and am not sure it works... you can try if you like... it would probably be good practice with flags... and here's a list of flags and their manipulators: http://cppreference.com/cppio_flags.html
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