C++ lambda運算式 （二）

標籤：init   ssi   cap   its   style   function   運算式   element   algo   

#include <functional>#include <iostream>int main(){   using namespace std;   int i = 3;   int j = 5;   // The following lambda expression captures i by value and   // j by reference.   function<int (void)> f = [i, &j] { return i + j; };   // Change the values of i and j.   i = 22;   j = 44;   // Call f and print its result.   cout << f() << endl;}

　　

 

可以看到i是拷貝值，j是引用值，所以是24，結果26

 

 

• 把lambda運算式當作參數傳送

#include <list>#include <algorithm>#include <iostream>int main(){    using namespace std;    // Create a list of integers with a few initial elements.    list<int> numbers;    numbers.push_back(13);    numbers.push_back(17);    numbers.push_back(42);    numbers.push_back(46);    numbers.push_back(99);    // Use the find_if function and a lambda expression to find the     // first even number in the list.    const list<int>::const_iterator result =         find_if(numbers.begin(), numbers.end(),[](int n) { return (n % 2) == 0; });//尋找第一個偶數    // Print the result.    if (result != numbers.end())     {        cout << "The first even number in the list is " << *result << "." << endl;    } else     {        cout << "The list contains no even numbers." << endl;    }}

 

C++ lambda運算式 （二）