


What are some practical examples of using C++ lambda expressions for data filtering and transformation?
Apr 18, 2024 am 09:15 AMIn 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.
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
std::vector<int> numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9}; // 使用 lambda 表達(dá)式過濾奇數(shù) std::vector<int> odd_numbers = std::filter(numbers.begin(), numbers.end(), [](int n) { return n % 2 != 0; });
2. Transform elements in a container
std::vector<double> squares = std::transform(numbers.begin(), numbers.end(), [](int n) { return n * n; });
3. Filter and transform associated containers
std::map<int, std::string> name_age = { {1, "John"}, {2, "Mary"}, {3, "Bob"}, {4, "Alice"} }; // 過濾年齡大于 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; });
4. Use lambda expressions in algorithms
std::sort(numbers.begin(), numbers.end(), [](int a, int b) { return a > b; }); // 從大到小排序
5. Passing lambda expressions as function parameters
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 << " "; }); // 打印出容器中的每個(gè)元素
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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