Kotlin is used to develop Android apps, server side apps, and much more. Kotlin is easy to learn, especially if you already know Java (it is 100 compatible with Java). This is equivalent to the foreach loop in languages like C#. Kotlin is a modern, trending programming language. The existence of this feature or lack thereof is the subject of recurring stackoverflow questions.For loop iterates through anything that provides an iterator. This feature exists in some form in Python, Rust, Go (backed into the language), and in many C++ libraries: ranges-v3, folly, boost::ranges ( indexed). Also, Id like to mention that mapIndexed is like map but with the index of the element, so you need to pass a function that transforms every element. We propose a view enumerate whose value type is a struct with 2 members index and value representing respectively the position and value of the elements in the adapted range. In your case the function passed as the parameter of mapIndexed was inferred to Any because you miss the else branch of your if statement. for (auto = std::tuple įor (auto = its_and_idx(foo) it != end ++it, ++i)Ĭ++ Standard proposal P2164 proposes to add views::enumerate, which would provide a view of a range giving both reference-to-element and index-of-element to a user iterating it. and than other solutions that require a counter with scope outside the for loop. Std::cout << x.index << ": " << x.item << std::endl Ĭ++17 and structured bindings makes this look OK - certainly better than some ugly mutable lambda with a local (Element&) mutable or whatever I've done before admitting that probably not everything should be shoehorned into for_each() et al. A templated free function allows you to create the wrapper class Iterator(typename T::iterator _it, size_t counter=0) : Custom iterator with minimal interface is what you will get inside of the for loop In the following example, we take a string in str1, and iterate over each character in this string using erator() method and For Loop. The return value of the operator* of the iterator, this To iterate over each character in the String in Kotlin, use erator() method which returns an iterator for characters in this string, and then use For Loop with this iterator. Below is a very minimal exemplary implementation to illustrate the idea: // Distributed under the terms of the GPLv2 or newer The idea behind is, that you build a wrapper struct with a custom iterator that does the counting. A good implementation of the feature you are requested can be found here:
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