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.