lst-0057-book.cpp
// https://godbolt.org/z/8GxPMEc5o
#include <iostream>
int main() {
int count = 0;
auto plus1 = [&count](int x) { // count as reference
++count; return x+1;
};
for(int i=0; i<5; ++i) { plus1(i); }
std::cout << "plus1 was called " << count << " times\n";
// Output: plus1 was called 5 times
}