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Apache C++ Standard Library Reference Guide


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A function that determines the type of distance used by an iterator.

NOTE -- This function is now obsolete. It is retained here to
support compilers that do not include partial specialization, but
will be dropped in a subsequent release.



The __distance_type() family of function templates returns a pointer to a value that is of the same type as that used to represent a distance between two iterators. The first of these takes an iterator of a particular type and returns a pointer to a default value of the difference_type for that iterator. The T* form of the function returns ptrdiff_t*.

Generic algorithms use this function to create local variables of the correct type. The __distance_type() functions are typically used like this:

The auxiliary function template allows the algorithm to extract a distance type from the first iterator and then use that type to perform some useful work.

See Also

Other iterator primitives: __iterator_category(), distance(), advance()

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