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:
1
2
3
4
5
 
template <class ForwardIterator, class Generator>
  void generate ( ForwardIterator first, ForwardIterator last, Generator gen )
{
  while (first != last)  *first++ = gen();
}


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

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
 
// 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;
}


A possible output:
myvector contains: 57 87 76 66 85 54 17 15
myvector contains: 1 2 3 4 5 6 7 8


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)