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function template
<algorithm>

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:
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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

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// 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.

See also