rangex

Factory to produce clear iterator with step and optional inclusive stop, which is used in for(auto i:range) / for(auto [index, value]: range)

Swift has very clear notations for range in loop:

//inclusive 5
for i in 1...5 {
    //print(i)
}
//downward inclusive 1, use 'to: 1' for exclusive
for i in stride(from: 5, through: 1, by: -1) {
    //print(i)
}

In C

/* inclusive 5 */
for (int i=1; i<=5; i++) {
    /* printf("%d ", i); */
}
/* downward inclusive 1 */
for (int i=5; i>=1; i--) {
    /* printf("%d ", i); */
}

And Rust:

// inclusive 5
for i in 1..=5 {
    // print!("{i} ")
}
// downward inclusive 5 (and 1)
for i in (1..=5).rev() {
    // print!("{} ", i);
}

And C++20:

#include <ranges>
// exclusive 6
for(auto value : std::views::iota(1, 6)) { // Generate values from 1 to 5, lazy computing
    // std::cout << value << std::endl; // #include <iostream>
}
// downward exclusive 6
for (int i : std::views::iota(1, 6) | std::views::reverse) {
    // std::cout << i << std::endl;
}

With rangex lib in C++20

#include "rangex_lib.h"
using namespace ns_rangex;

//Inclusive iterated range:
for (auto i : rangex(1, 5, true)) {
    // std::printf()
}
//Inclusive downward step -1
for (auto i : rangex(5, 1, true, -1)) {
    // std::printf()
}
//Templated typename
for (auto i : rangex<int>(1, 6)) {
    // 1,2,3,4,5
}

An indexed range will provide index for iteration start from 0 Indexed range in Swift

let elements = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]
for (index, element) in elements.enumerated() {
    //print("Index: \(index), Element: \(element)")
}

Indexed range in Rust

    let elements = vec![10, 20, 30, 40, 50, 60, 70, 80, 90, 100];
    for (index, element) in elements.iter().enumerate() {
        //println!("Index: {}, Element: {}", index, element);
    }

Indexed range in std C++20:

    // Create a vector of elements
    std::vector<int> elements = {10, 20, 30, 40, 50, 60, 70, 80, 90, 100};

    // Create an indexed range using iota and a custom zip view
    auto indexed_range = std::views::iota(0, static_cast<int>(elements.size()))
                       | std::views::transform([&](int index) {
                             return std::pair{index, elements[index]};
                         });

    // Iterate over the indexed range and print the index and corresponding element
    for (const auto& [index, element] : indexed_range) {
        std::cout << "Index: " << index << ", Element: " << element << std::endl;
    }

Indexed range in rangex C++20

#include "rangex_lib.h"
using namespace ns_rangex;

for (auto [i, v] : rangex<int, true>(5, 1, true, -1)) {
    // std::printf("%u %u", i, v)
}

In Swift, by in (from, to, by) must be signed say Int, Float, Double from, to, through must be of same type, by must be of the signed type with them. If from <= to/through and step < 0, or from >= to/through and step > 0, for loop will do nothing. If step is 0, Swift will panic