for_each (STL Samples)
Illustrates how to use the for_each Standard Template Library (STL) function in Visual C++.
template<class InputIterator, class Function> inline
Function for_each(
InputIterator First,
InputIterator Last,
Function F
)
Remarks
注意
The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.
The for_each algorithm calls Function F for each element in the range [First, Last) and returns the input parameter F. This function does not modify any elements in the sequence.
Example
// foreach.cpp
// compile with: /EHsc
//
// Functions:
// for_each - Calls function F for every element in a range.
//
// begin - Returns an iterator that points to the first element
// in a sequence.
//
// end - Returns an iterator that points one past the end of
// a sequence.
// disable warning C4786: symbol greater than 255 characters,
// okay to ignore
#pragma warning(disable: 4786)
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
// prints the cube of integer n
void PrintCube(int n)
{
cout << n * n * n << " " ;
}
int main()
{
const int VECTOR_SIZE = 8 ;
// Define a template class vector of integers
typedef vector<int > IntVector ;
//Define an iterator for template class vector of integer
typedef IntVector::iterator IntVectorIt ;
IntVector Numbers(VECTOR_SIZE) ; //vector containing numbers
IntVectorIt start, end, it ;
int i ;
// Initialize vector Numbers
for (i = 0; i < VECTOR_SIZE; i++)
Numbers[i] = i + 1 ;
start = Numbers.begin() ; // location of first
// element of Numbers
end = Numbers.end() ; // one past the location
// last element of Numbers
// print content of Numbers
cout << "Numbers { " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << " }\n" << endl ;
// for each element in the range [first, last)
// print the cube of the element
for_each(start, end, PrintCube) ;
cout << "\n\n" ;
}
Numbers { 1 2 3 4 5 6 7 8 }
1 8 27 64 125 216 343 512
Requirements
Header: <algorithm>