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What is the use of lambda expressions in C++?

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2024-04-17 15:45:01556browse

In C, Lambda expressions are used as anonymous functions and have a wide range of uses: simplifying the creation of anonymous functions and passing them as function parameters to perform ad hoc processing optimization algorithms (such as specifying comparison functions)

Lambda 表达式在 C++ 中有什么用途?

Use and practice of using Lambda expressions in C

Introduction
Lambda expressions are a powerful tool in C that allow anonymous functions Passed as a parameter or stored in a variable. They are useful in a variety of use cases, from data processing to algorithm optimization.

Purpose

  • Simplify the creation of anonymous functions: Lambda expressions provide a concise syntax that simplifies the creation of anonymous functions.
  • As function parameters: Lambda expressions can be passed as parameters to other functions, allowing for highly customizable callbacks.
  • Temporary processing:Lambda expressions are very useful for small tasks that do not need to be named or reused.
  • Algorithm optimization: Lambda expressions can be used to optimize algorithms, such as using [std::sort](https://www.cppreference.com/w/cpp/algorithm/sort ) specifies a comparison function when sorting a collection.

Practical example

Example 1: Create an anonymous function

auto sum = [](int a, int b) { return a + b; };

This will create a simple lambda expression expression that adds two integers.

Example 2: As function parameters

void for_each(std::vector<int>& v, std::function<void(int)> f) {
  for (auto& i : v) {
    f(i);
  }
}

This function accepts a vector and a function as parameters and calls the function for each element in the vector.

Example 3: Temporary processing

std::cout << std::find_if(v.begin(), v.end(), [](int i) { return i % 2 == 0; })->first;

This code uses a lambda expression to find the first even number in a vector.

Example 4: Algorithm Optimization

std::sort(v.begin(), v.end(), [](int a, int b) { return a > b; });

This example uses lambda expressions to sort a vector in descending order.

Conclusion
Lambda expressions provide powerful capabilities in C, allowing easy creation and use of anonymous functions. They are useful in a wide range of use cases, from simple tasks to complex algorithm optimization.

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