Using "this" to define a function within parameters

Asked Apr 17 '17 at 23:39

Active Apr 17 '17 at 23:42

Viewed 33 times

I've been having issues compiling some code from a library due to a particular line,

std::sort(indices.begin(), indices.end(), [this](size_t i1, size_t i2) {return (*this)[i1] < (*this)[i2];});

The error thrown is:

 expected expression

Referring specifically to the first bracket around "this." I've never seen "this" used in this format before. Does this technically work, and if so, how? The function used is the standard sort function, so there should be a function pointer where this appears instead.

Thanks!

edited Apr 17 '17 at 23:42

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asked Apr 17 '17 at 23:39

Beau Horenberger

1

Even before C++11, there was no requirement that the predicate be a function pointer. – Barry Apr 17 '17 at 23:41
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Does your compiler support C++11 or later, and do you have it enabled? – aschepler Apr 17 '17 at 23:41

Using "this" to define a function within parameters

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