std::iota
From Cppreference
| Defined in header <numeric>
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| template< class ForwardIterator, class T >
void iota( ForwardIterator first, ForwardIterator last, T value ); |
(C++11 feature) | |
Fills the range [first, last) with sequentially increasing values, starting with value and repetitively evaluating ++value
Equivalent operation:
*(d_first) = value; *(d_first+1) = ++value; *(d_first+2) = ++value; *(d_first+3) = ++value; ...
Contents |
[edit] Parameters
| first, last | - | the range of elements to sum |
| value | - | initial value to store, the expression ++value must be well-formed |
[edit] Return value
(none)
[edit] Complexity
Exactly last - first increments and assignments.
[edit] Equivalent function
template<class ForwardIterator, class T> void iota(ForwardIterator first, ForwardIterator last, T value) { while(first != last) { *first++ = value; ++value; } } |
[edit] Example
The following example applies std::random_shuffle to a vector of iterators to a std::list since std::random_shuffle cannot be applied to an std::list directly. std::iota is used to create the vector.
#include <numeric> #include <algorithm> #include <list> #include <vector> #include <iostream> int main() { std::list<int> l(10); std::iota(l.begin(), l.end(), -4); std::vector<std::list<int>::iterator> v(l.size()); std::iota(v.begin(), v.end(), l.begin()); std::random_shuffle(v.begin(), v.end()); std::cout << "Contents of the list: "; for(auto n: l) { std::cout << n << ' '; } std::cout << '\n'; std::cout << "Contents of the list, shuffled: "; for(auto i: v) { std::cout << *i << ' '; } std::cout << '\n'; }
Output:
Contents of the list: -4 -3 -2 -1 0 1 2 3 4 5 Contents of the list, shuffled: 0 -1 3 4 -4 1 -2 -3 2 5
[edit] See also
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assigns a range of elements a certain value (function template) |
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saves the result of a function in a range (function template) |
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