std::for_each

template <class InputIterator, class Function> Function for_each (InputIterator first, InputIterator last, Function fn);

Apply function to range

Applies function fn to each of the elements in the range [first,last).

The behavior of this template function is equivalent to:

template<class InputIterator, class Function>
 Function for_each(InputIterator first, InputIterator last, Function fn)
{
 while (first!=last) {
 fn (*first);
 ++first;
 }
 return fn; // or, since C++11: return move(fn);
}

Parameters

first, last: Input iterators to the initial and final positions in a sequence. The range used 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.
fn: Unary function that accepts an element in the range as argument.
This can either be a function pointer or a move constructible function object.
Its return value, if any, is ignored.

Return value

Returns fn.

Returns fn, as if calling std::move(fn).

Example

// for_each example
#include <iostream> // std::cout
#include <algorithm> // std::for_each
#include <vector> // std::vector
void myfunction (int i) { // function:
 std::cout << ' ' << i;
}
struct myclass { // function object type:
 void operator() (int i) {std::cout << ' ' << i;}
} myobject;
int main () {
 std::vector<int> myvector;
 myvector.push_back(10);
 myvector.push_back(20);
 myvector.push_back(30);
 std::cout << "myvector contains:";
 for_each (myvector.begin(), myvector.end(), myfunction);
 std::cout << '\n';
 // or:
 std::cout << "myvector contains:";
 for_each (myvector.begin(), myvector.end(), myobject);
 std::cout << '\n';
 return 0;
}

Output:

myvector contains: 10 20 30
myvector contains: 10 20 30

Complexity

Linear in the distance between first and last: Applies fn to each element.

Data races

The objects in the range [first,last) are accessed (each object is accessed exactly once).
These objects may be modified if InputIterator is a mutable iterator type and fn is not a constant function.

Exceptions

Throws if fn throws or if any of the operations on iterators throws.
Note that invalid arguments cause undefined behavior.