结合C++11新特性来学习C++中lambda表达式的用法

// compile with: /W4 /EHsc
#include <algorithm>
#include <iostream>
#include <vector>
#include <string>

using namespace std;

template <typename C> void print(const string& s, const C& c) {
 cout << s;

 for (const auto& e : c) {
 cout << e << " ";
 }

 cout << endl;
}

void fillVector(vector<int>& v)
{
 // A local static variable.
 static int nextValue = 1;

 // The lambda expression that appears in the following call to
 // the generate function modifies and uses the local static 
 // variable nextValue.
 generate(v.begin(), v.end(), [] { return nextValue++; });
 //WARNING: this is not thread-safe and is shown for illustration only
}

int main()
{
 // The number of elements in the vector.
 const int elementCount = 9;

 // Create a vector object with each element set to 1.
 vector<int> v(elementCount, 1);

 // These variables hold the previous two elements of the vector.
 int x = 1;
 int y = 1;

 // Sets each element in the vector to the sum of the 
 // previous two elements.
 generate_n(v.begin() + 2,
 elementCount - 2,
 [=]() mutable throw() -> int { // lambda is the 3rd parameter
 // Generate current value.
 int n = x + y;
 // Update previous two values.
 x = y;
 y = n;
 return n;
 });
 print("vector v after call to generate_n() with lambda: ", v);

 // Print the local variables x and y.
 // The values of x and y hold their initial values because 
 // they are captured by value.
 cout << "x: " << x << " y: " << y << endl;

 // Fill the vector with a sequence of numbers
 fillVector(v);
 print("vector v after 1st call to fillVector(): ", v);
 // Fill the vector with the next sequence of numbers
 fillVector(v);
 print("vector v after 2nd call to fillVector(): ", v);
}

  vector v after call to generate_n() with lambda: 1 1 2 3 5 8 13 21 34
x: 1 y: 1
vector v after 1st call to fillVector(): 1 2 3 4 5 6 7 8 9
vector v after 2nd call to fillVector(): 10 11 12 13 14 15 16 17 18