Example of the lambda functions in c++0x

sum.cpp

// Copyright 2011 Vaclav Bohac <[email protected]>. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


#include <cstdlib>
#include <iostream>
#include <functional>

using namespace std;


/**
 * Invokes fn for each number.
 * @param  int* beginning of the array
 * @param  int  length of the array
 * @param  void(int) callback function
 * @return void
 */
void each(int* numbers, int length, function<void(int)> fn) {
	int i, l = length > 0 ? length : 0;
	for (i = 0; i < l; i++) {
		fn( numbers[i] );
	}
}


int main() {
	int sum = 0, nums[] = {1, 2, 3},
		l = sizeof(nums) / sizeof(int);

	each(nums, l, [&](int number) {
		sum += number; // Sum is closured and writeable. 
	});

	cout << sum << endl; // Prints 6

	return 0;
}