1. Basic form
[capture](parameters)->return-type {body}
例如：
auto func = [](){ cout << "hello,world"; };
1. “[ ]” -- capture specifier, indicating the beginning of a lambda expression
- [ ] -- Do not intercept any variables
- [&] -- Intercept all variables in the external scope and use them as references in the function body
- [=] --Intercept all variables in the external scope and make a copy for use in the function body
- [=, &foo] -- Intercept all variables in the external scope and make a copy for use in the function body, but use references to the foo variable
- [bar] -- Intercept the bar variable and copy a copy for use in the function body without intercepting other variables.
- [x, &y] -- x is passed by value, y is passed by reference
- [this] -- Intercept the this pointer in the current class. This option is added by default if & or = is already used.
2. "( )" -- parameter list, that is, the parameters of this anonymous lambda function
[](const DMatch &m1, const DMatch &m2) { return m1.distance < m2.distance; }
3. "return-type" -- return type, if there is no return type, omit
4. "{ }" -- function body part