Книга: Standard Template Library Programmer

generate_n

generate_n

Category: algorithms

Component type: function

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

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.

Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h.

• 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.

• n >= 0.

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

Linear. Exactly n invocations of gen. [1]

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

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

[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.

copy, fill, fill_n, generate, iota

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