generate_n
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| 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 the standard header algorithm, and in the nonstandard
backward-compatibility header 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.
See also
copy, fill, fill_n, generate, iota
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