C++ | Steven Engelhardt

C++ c win32

Published: 2005-09-07

Consider the following piece of code (adapted from a real-world bug):

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BOOL IsDirectory(LPCTSTR strPathName)
{
    DWORD dwAtts = GetFileAttributes(strPathName);
    if (dwAtts == INVALID_FILE_ATTRIBUTES)
        return FALSE;
    return (dwAtts == FILE_ATTRIBUTE_DIRECTORY);
}

This function will work most of the time, but every now and again it will run across a directory which it will claim isn’t one. Why?

C++ c++

Published: 2005-09-06

Use Constant References For Input-Only Parameters, Pointers Otherwise

This is a style issue, so there is no right or wrong, but I suggest using a const reference for an input-only paramater to a C++ function and a pointer for an input/output or output-only parameter. This makes it slightly more obvious that the parameter might be modified by the function.

Example:

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ReturnType Function
    (
    const ParamType& inputParam,
    ParamType* inputOutputParam,
    ParamType* outputParam
    )
{
    // ...
}

void User()
{
    ParamType inputParam;
    ParamType inputOutputParam;
    ParamType outputParam;

    // Note the &s -- this is a bit of a warning something
    // might happen to inputOutputParam or outputParam...
    ReturnType ret = Function
        (
        inputParam,
        &inputOutputParam,
        &outputParam
        );
}

Write Functions Which Take Iterators, Not Collections

C++ c++ stl

Published: 2005-09-05

Write Functions Which Take Iterators, Not Collections

If my experience is typical, this is a very common construct:

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ReturnType Function
    (
    const std::vector<T>& container
    )
{
    typedef std::vector<T>::const_iterator iterator_t;
    for (iterator_t iter = container.begin();
         iter != container.end();
         ++iter)
    {
        // Work with *iter
    }
}

The problem with this construct is that you have forced a container choice upon the user of your function. Slightly better, and basically your only choice when interoping with C, is this: