How to use lambda expressions in C++?

Lambda expressions are anonymous functions in C that are used to create one-time functions. They access external scope variables through capture lists and can receive parameters and define return types. Lambda expressions are often used to quickly create or pass functions at runtime. They have access to Lvalues ​​and Rvalues, and can be stateful or stateless.

Usage of Lambda expression in C

Lambda expression is a powerful feature in C that allows you to define it once anonymous function. They are typically used where functions need to be created quickly or passed around at runtime.

Grammar

The general syntax of Lambda expression is:

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

Among them:

• capture list : This is a capture list that specifies variables in the outer scope that the lambda expression can access.
• parameters: This is the parameter list for the lambda expression function.
• return_type: This is the return type of the lambda expression function.
• body: This is the function body of the lambda expression function.

Practical case

Let us create a lambda expression to convert the string to uppercase:

auto to_upper = [](const std::string& s) -> std::string {
    std::string result;
    for (char c : s) {
        result.push_back(std::toupper(c));
    }
    return result;
};

We can Using this lambda expression, for example:

std::string my_string = "hello, world";
std::string upper_string = to_upper(my_string);

upper_string will now contain the converted string "HELLO, WORLD".

Note

• Lambda expressions are anonymous functions that cannot be named.
• The variables in the capture list must be variables defined in the external scope.
• Lambda expressions can access Lvalue and Rvalue.
• Lambda expressions can be stateful or stateless. Stateful lambda expressions capture variables and modify them, while stateless lambda expressions only read variables.

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