lambda表达式书写格式:[capture-list] (parameters) mutable -> return-type { statement }
int main()
{
int a = 0, b = 2;
double rate = 2.555;
auto add1 = [](int x, int y)->int {return x + y; };
auto add2 = [](int x, int y) {return x + y; };//返回值类型明确情况下,也可省略,由编译器对返回类型进行推导。
}
auto add3 = [rate](int x, int y) {return (x + y)* rate; };
int a = 0;
int b = 1;
int c = 2;
int d = 3;
const int e = 1;
cout << &e << endl;
// 引用的方式捕捉所有对象,除了a
// a用传值的方式捕捉
//捕捉所有对象auto func = [&]{函数体};
auto func = [&, a] {
//a++;fail
b++;
c++;
d++;
//e++;
cout << &e << endl;
//这里程序是会报错的,可以这样理解:因为其参数默认是带const的,不能被修改
int x = 0, y = 2;
auto swap1 = [add1](int& x, int& y) {
int tmp = x;
x = y;
y = tmp;
cout << add1(x, y) << endl;
};
swap1(a, b);
int x = 0, y = 2;
auto swap1 = [x, y]() mutable {
// mutable让捕捉的x和y可以改变了,
// 但是他们依旧是外面x和y的拷贝
int tmp = x;
x = y;
y = tmp;
};
swap1();
int x = 0, y = 2;
auto swap1 = [x, y]() mutable {
// mutable让捕捉的x和y可以改变了,
// 但是他们依旧是外面x和y的拷贝
int tmp = x;
x = y;
y = tmp;
};
swap1();
// 引用的方式捕捉
int x = 0, y = 2;
auto swap2 = [&x, &y](){
int tmp = x;
x = y;
y = tmp;
};
swap2();