< cpp‎ | algorithm
Defined in header <algorithm>
template< class ForwardIt, class Generator >
void generate( ForwardIt first, ForwardIt last, Generator g );

Assigns each element in range [first, last) a value generated by the given function object g.


[edit] Parameters

first, last - the range of elements to generate
g - generator function object that will be called.

The signature of the function should be equivalent to the following:

Ret fun();

The type Ret must be such that an object of type ForwardIt can be dereferenced and assigned a value of type Ret. ​

Type requirements
ForwardIt must meet the requirements of ForwardIterator.

[edit] Return value


[edit] Complexity

Exactly std::distance(first, last) invocations of g() and assignments.

[edit] Possible implementation

template<class ForwardIt, class Generator>
void generate(ForwardIt first, ForwardIt last, Generator g)
    while (first != last) {
        *first++ = g();

[edit] Example

The following code fills a vector with random numbers:

#include <algorithm>
#include <iostream>
#include <cstdlib>
int main()
    std::vector<int> v(5);
    std::generate(v.begin(), v.end(), std::rand); // Using the C function rand()
    std::cout << "v: ";
    for (auto iv: v) {
        std::cout << iv << " ";
    std::cout << "\n";
    // Initialize with default values 0,1,2,3,4 from a lambda function
    // Equivalent to std::iota(v.begin(), v.end(), 0);
    int n = {0};
    std::generate(v.begin(), v.end(), [&n]{ return n++; }); 
    std::cout << "v: ";
    for (auto iv: v) {
        std::cout << iv << " ";
    std::cout << "\n";

Possible output:

v: 52894 15984720 41513563 41346135 51451456
v: 0 1 2 3 4

[edit] See also

assigns a range of elements a certain value
(function template)
saves the result of N applications of a function
(function template)
parallelized version of std::generate
(function template)