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Turning remove_if into remove_not_if

开发者 https://www.devze.com 2023-01-18 23:52 出处:网络
How can I reverse a predicate\'s return value, and remove the elements that return false instead of true?

How can I reverse a predicate's return value, and remove the elements that return false instead of true?

Here is my code:

headerList.remove_if(FindName(name));

(please ignore lack of erase)

with FindName a simple functor:

struct FindName
{
    CString m_NameToFind;

    FindInspectionNames(const CString &nameToFind)
    {
        m_NameToFind = nameToFind;
    }

    bool operator()(const CHeader &header)
    {
        if(header.Name == m_NameToFind)
        {
            return true;
        }

        return false;
    }
};

I would like somethin开发者_如何学Cg like:

list.remove_if(FindName(name) == false);

Not yet using c++0x, so lambdas not allowed, sadly. I'm hoping there is a nicer solution than writing a NotFindName functor.


Check not1 in the <functional> header:

headerList.remove_if( std::not1( FindName( name ) ) );

Oh, and this:

if(header.Name == m_NameToFind)
{
    return true;
}

return false;

Please don't do that.

return ( header.Name == m_NameToFind );

That's much better, isn't it?


alternatively you could use boost bind so you don't have to write that unary_function struct:

bool header_has_name (const CHeader& h, const CString& n) {return h.name == n;}

headerList.remove_if (boost::bind (header_has_name, _1, "name"));

and for remove_if_not:

headerList.remove_if (!boost::bind (header_has_name, _1, "name"));

You could even use std::equal() to avoid the header_has_name function completely but at that point it becomes a little bit ugly.


Unfortunately I think writing a NotFindName functor is your best bet.

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