cplusplus lambda functions

所谓lambda，在c++中就是一个闭包函数:能够捕获域内变量的未命令的函数对象。

语法

# 语法
1 [ capture-list ] ( params ) mutable(optional) exception attribute -> ret { body }
2 [ capture-list ] ( params ) -> ret { body }
3 capture-list ] ( params ) { body }
4 [ capture-list ] { body }

  1. 完整声明。

  2. lambda常量的声明:以复制的方式捕获对象，对象不可修改。

  3. 省略了尾部的返回类型:闭包的operator()的返回类型根据以下规则确定:
    c++14之前:
    • if the body consists of nothing but a single return statement with an expression, the return type is the type of the returned expression (after rvalue-to-lvalue, array-to-pointer, or function-to-pointer implicit conversion) .
    • 否则，返回类型为void。
      c++14或之后:
      The return type is deduced from return statements as if for a function whose return type is declared auto.
  4. Omitted parameter list: function takes no arguments, as if the parameter list was () .

Refrence

refrence from cppreference