lambda /ˈlæm.də/：the 11th letter of the Greek alphabet (希腊语字母表的第 11 个字母)

https://learn.microsoft.com/en-us/cpp/cpp/lambda-expressions-in-cpp

1. Parts of a lambda expression (Lambda 表达式的各个部分)

This illustration shows the parts of lambda syntax:

1. capture clause (Also known as the lambda-introducer in the C++ specification)

2. parameter list Optional (可选) (Also known as the lambda declarator)

3. mutable specification Optional (可选)

4. exception-specification Optional (可选)

5. trailing-return-type Optional (可选)

6. lambda body

1.2. Parameter list (Optional)

Lambdas can both capture variables and accept input parameters.
lambda 既可以捕获变量，也可以接受输入参数。

A parameter list (lambda declarator in the Standard syntax) is optional and in most aspects resembles the parameter list for a function.
参数列表 (在标准语法中称为 lambda 声明符) 是可选的，它在大多数方面类似于函数的参数列表。

#include <stdio.h>

int main(void) {

	auto add_func = [](const int first, const int second) {
		return first + second;
	};

	const int result = add_func(2, 3);

	printf("result = %d\n", result);

	return 0;
}

result = 5
请按任意键继续. . .

lambda could own default arguments.

#include <stdio.h>

int main(void) {

	auto add_func = [](const int first, const int second = 12) {
		return first + second;
	};

	const int result = add_func(3);

	printf("result = %d\n", result);

	return 0;
}

result = 15
请按任意键继续. . .

References

[1] Yongqiang Cheng, https://yongqiang.blog.csdn.net/