Home Backend Development C++ What are some practical examples of using C++ lambda expressions for data filtering and transformation?

What are some practical examples of using C++ lambda expressions for data filtering and transformation?

Apr 18, 2024 am 09:15 AM
c++ Data filtering

In C, lambda expressions can be used to easily filter and transform data. For example, you can use lambda expressions to filter odd elements in a container, transform elements in a container, filter and transform associative containers, use lambda expressions in algorithms, and pass lambda expressions as function arguments. These methods can make data processing tasks simpler and more efficient.

使用 C++ lambda 表达式进行数据过滤和转换有哪些实战案例?

A practical case of using C lambda expressions for data filtering and transformation

Lambda expressions are very useful in C, especially It's when filtering and transforming data. Here are some examples of practical applications:

1. Filter elements in a container

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std::vector<int> numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9};

 

// 使用 lambda 表达式过滤奇数

std::vector<int> odd_numbers = std::filter(numbers.begin(), numbers.end(), [](int n) { return n % 2 != 0; });

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2. Transform elements in a container

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std::vector<double> squares = std::transform(numbers.begin(), numbers.end(), [](int n) { return n * n; });

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3. Filter and transform associated containers

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std::map<int, std::string> name_age = {

    {1, "John"},

    {2, "Mary"},

    {3, "Bob"},

    {4, "Alice"}

};

 

// 过滤年龄大于 2 的人

auto filtered_name_age = std::map<int, std::string>(name_age.begin(), name_age.end(), [](const std::pair<int, std::string>& p) { return p.second.size() > 2; });

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4. Use lambda expressions in algorithms

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std::sort(numbers.begin(), numbers.end(), [](int a, int b) { return a > b; }); // 从大到小排序

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5. Passing lambda expressions as function parameters

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void process_data(std::vector<int>& data, std::function<void(int)> callback) {

    for (int& element : data) {

        callback(element);

    }

}

 

process_data(numbers, [](int n) { std::cout << n << " "; }); // 打印出容器中的每个元素

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These are just some of the ways in C to use lambda expressions for data filtering and transformation. By leveraging lambda expressions, you can write concise and powerful code to handle various data manipulation tasks.

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