How to formulate the parameter list of C++ lambda expression?

The parameter list syntax of Lambda expression is: [capture-list](parameters) -> return-type { body }, where: capture-list captures external variables. parameters is the parameter list. return-type is the return type. body is the function body.

C Parameter list formulation of Lambda expression

Lambda expression is a concise and powerful inline function in C , external variables can be captured and stored on the stack. The parameter list syntax of a lambda expression is as follows:

[capture-list](parameters) -> return-type { body }

capture-list Specifies the external variable to be captured, which can have the following values:

• [ =]: Capture all external variables
• [&]: Capture all external variables and pass them as references
• [parameter1, parameter2, . ..]: Capture the specified external variables
• [parameter1, parameter2, ..., &parameter3, &parameter4, ...]: Capture both the specified variables and The reference form captures other variables

parameters Specifies the parameter list of the lambda expression, the syntax is the same as the parameter list of the ordinary function.

return-type Specifies the return type of the lambda expression, which can be any valid C data type.

body is the function body of the lambda expression and contains the code to be executed.

Practical case

Consider a function that needs to sort a list of integers. We can define a comparison function using a lambda expression:

auto compare = [](int a, int b) { return a > b; };

In this example, the lambda expression captures the external variables a and b.

We can also use lambda expressions to create anonymous functions and execute them immediately:

auto print_name = [](string name) { cout << "Hello, " << name << endl; };
print_name("John Doe");

This lambda expression captures the external variable name and passes it as a parameter The cout function is given.

By customizing the capture-list and argument list, lambda expressions provide powerful tools for writing concise, flexible, and reusable code in C.

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