operator<

[Morea]

how do I write that for a class X?
I'm gonna use qSort.

bool X::operator<(const X& a)
{
return number < a.number;}

bool X::operator<(const X& a)
{
return number < a.number;}

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don't work.

/usr/include/qt4/QtCore/qalgorithms.h:118: error: passing `const X' as
`this' argument of `bool X:perator<(const X&)' discards
qualifiers

[wysota]

Try:

bool X::operator<(const X& a) const {
  return number < a.number;
}

bool X::operator<(const X& a) const {
  return number < a.number;
}

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[Morea]

Super!
That brings me to the somewhat related non-C++ question, How do you search google for the exact text

operator<

operator<

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it always ignores the < at the end.

[wysota]

Try with quotes -- "operator<"

[Morea]

But then the first results doesn't contain the string operator< and that is to me a proof of that operator< with quotes is not really working.