Learn Higher Order Functions | Advanced Functional Patterns

Higher-order functions are a fundamental pattern in functional programming, and C++ supports them through its type system and standard library utilities. A higher-order function is any function that either takes one or more functions as arguments, or returns a function as its result. This enables you to write flexible, reusable code by abstracting behavior as parameters. Higher-order functions are widely used in C++ to customize algorithms, manage callbacks, and implement strategies or policies in a generic way. By treating functions as first-class citizens, you can decouple control flow from implementation details, making your code more modular and expressive.

main.cpp


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#include <iostream>
#include <functional>
#include <string>

// A higher-order function that takes a function as a parameter
void processString(const std::string& input, const std::function<void(const std::string&)>& func) {
    // Call the passed-in function with the input string
    func(input);
}

// A simple function to print a string in uppercase
void printUppercase(const std::string& s) {
    for (char c : s) {
        std::cout << static_cast<char>(std::toupper(c));
    }
    std::cout << std::endl;
}

int main() {
    std::string message = "Hello, Higher-Order Functions!";
    // Pass printUppercase as a function pointer
    processString(message, printUppercase);

    // Pass a lambda that prints the string length
    processString(message, [](const std::string& s) {
        std::cout << "Length: " << s.length() << std::endl;
    });

    return 0;
}

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Section 3. Chapter 1

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main.cpp


              12345678910111213141516171819202122232425262728293031
            
#include <iostream>
#include <functional>
#include <string>

// A higher-order function that takes a function as a parameter
void processString(const std::string& input, const std::function<void(const std::string&)>& func) {
    // Call the passed-in function with the input string
    func(input);
}

// A simple function to print a string in uppercase
void printUppercase(const std::string& s) {
    for (char c : s) {
        std::cout << static_cast<char>(std::toupper(c));
    }
    std::cout << std::endl;
}

int main() {
    std::string message = "Hello, Higher-Order Functions!";
    // Pass printUppercase as a function pointer
    processString(message, printUppercase);

    // Pass a lambda that prints the string length
    processString(message, [](const std::string& s) {
        std::cout << "Length: " << s.length() << std::endl;
    });

    return 0;
}

Everything was clear?

Thanks for your feedback!

Section 3. Chapter 1