generate
function template
<algorithm>
template <class ForwardIterator, class Generator>
void generate ( ForwardIterator first, ForwardIterator last, Generator gen );
Generate values for range with function
Sets the value of the elements in the range [first,last) to the value returned by successive calls to gen.
The behavior of this function template is equivalent to:
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template <class ForwardIterator, class Generator>
void generate ( ForwardIterator first, ForwardIterator last, Generator gen )
{
while (first != last) *first++ = gen();
}
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Parameters
- first, last
- Forward iterators to the initial and final positions in a sequence. The range affected is [first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
- gen
- Generator function that takes no arguments and returns some value to be stored as element value. This can either be a pointer to a function or an object whose class overloads operator().
Return value
none
Example
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// generate algorithm example
#include <iostream>
#include <algorithm>
#include <vector>
#include <ctime>
#include <cstdlib>
using namespace std;
// function generator:
int RandomNumber () { return (rand()%100); }
// class generator:
struct c_unique {
int current;
c_unique() {current=0;}
int operator()() {return ++current;}
} UniqueNumber;
int main () {
srand ( unsigned ( time(NULL) ) );
vector<int> myvector (8);
vector<int>::iterator it;
generate (myvector.begin(), myvector.end(), RandomNumber);
cout << "myvector contains:";
for (it=myvector.begin(); it!=myvector.end(); ++it)
cout << " " << *it;
generate (myvector.begin(), myvector.end(), UniqueNumber);
cout << "\nmyvector contains:";
for (it=myvector.begin(); it!=myvector.end(); ++it)
cout << " " << *it;
cout << endl;
return 0;
}
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A possible output:
myvector contains: 57 87 76 66 85 54 17 15
myvector contains: 1 2 3 4 5 6 7 8
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Complexity
Linear: Invokes gen and assigns that value as many times as the number of elements in the range [first,last).
See also
| generate_n | Generate values for sequence with function (function template) |
| fill | Fill range with value (function template) |
| for_each | Apply function to range (template function) |
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