Introduction to Data Projection Techniques in C++

#include <iostream>
#include <vector>
#include <algorithm>

// Function to get a number's square
int square(int n) {
    return n * n;
}

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};  // our data stream
    std::vector<int> squared_numbers(numbers.size());

    // std::transform applies the square function to each number in the vector
    std::transform(numbers.begin(), numbers.end(), squared_numbers.begin(), square);

    // Print squared numbers
    for (int n : squared_numbers) {
        std::cout << n << " ";
    }
    // Output: 1 4 9 16 25

    return 0;
}

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cctype>

// Function to convert a string to lowercase
std::string to_lowercase(std::string s) {
    std::transform(s.begin(), s.end(), s.begin(), ::tolower);
    return s;
}

int main() {
    std::vector<std::string> sentences = {"HELLO WORLD", "C++ IS FUN", "I LIKE PROGRAMMING"};  // our data stream
    std::vector<std::string> lower_sentences(sentences.size());

    // std::transform applies the lambda function to each sentence in the vector
    std::transform(sentences.begin(), sentences.end(), lower_sentences.begin(),
                   [](std::string s) { return to_lowercase(s); });

    // Print lowercased sentences
    for (const std::string& sentence : lower_sentences) {
        std::cout << sentence << "\n";
    }
    // Output: hello world
    //         c++ is fun
    //         i like programming

    return 0;
}