generate_n


Category: algorithms	Component type: function

Prototype

template <class OutputIterator, class Size, class Generator>
OutputIterator generate_n(OutputIterator first, Size n, Generator gen);

Description

Generate_n assigns the result of invoking gen, a function object that takes no arguments, to each element in the range [first, first+n). [1] The return value is first + n.

Definition

Defined in algo.h.

Requirements on types

OutputIterator is a model of Output Iterator.
Size is an integral type (either signed or unsigned).
Generator is a model of Generator.
Generator's result type is convertible to a type in OutputIterator's set of value types.

Preconditions

n >= 0.
There is enough space to hold n values. That is, [first, first+n) is a valid range.

Complexity

Linear. Exactly n invocations of gen. [1]

Example

Print 100 random numbers, using the C standard library function rand.

generate_n(ostream_iterator<int>(cout, "\n"), 100, rand);

Notes

[1] The function object gen is invoked n times (once for each iterator in the range [first, first+n)), as opposed to just being invoked a single time outside the loop. This distinction is important because a Generator need not return the same result each time it is invoked; it is permitted to read from a file, refer to and modify local state, and so on.