What does the following do?

This is a discussion on What does the following do? within the C++ Programming forums, part of the General Programming Boards category; If an "if" is used in the following way what does it do? Code: if(variable_name) { // What to do. ...

  1. #1
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    What does the following do?

    If an "if" is used in the following way what does it do?

    Code:
    if(variable_name)
    {
    // What to do.
    }

  2. #2
    C++ Witch laserlight's Avatar
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    variable_name is converted to bool, and then the check for true/false happens.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
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  3. #3
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    So it looks if the variable is set?

  4. #4
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by Kitt3n
    So it looks if the variable is set?
    No. It converts the variable to type bool. What exactly that means depends on the type of the variable, and its value, e.g., a null pointer is converted to false, but a non-null pointer is converted to true.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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