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Rust-04: More operators and loops

In the last post we improved the simple program to be extendable with other operators. In this post we will implement more operators and a loop. Let’s start with the simple task: adding more operators. To support more operators we have to change two parts of the calculator, the parsing and the evaluation. First let’s look into changing the parser. For this we simply add the new operators (-*/) to the regex inside Operation::from_string. Continue reading

Rust-03: Improving the simple program

In the last post we created a simple program that would accept an input like 5+5 and calculates the result. In this post we will improve this program. To prepare for adding more operators we need to improve the input-parsing. Currently, we just split the input-string at the plus-sign. If we want to know the operator, we have to choose another approach. In this case I chose regex: #[derive(Debug)]struct Operation{left: i32,operator: char,right: i32,}implOperation{fn from_string(input: &String)-> Option<Operation>{letregex=Regex::new(r"^\s*(\d+)\s*([+])\s*(\d+)\s*$"). Continue reading

Rust-02: The beginning

At first, I didn’t like Rust. Managing memory myself is something I don’t want to do. After a first look at Rust and setting it aside for a few weeks, it appeared back on my radar. I thought: “This time I’m looking deeper into it”. So I started by reading the Rust Book; and I’m still reading it and find new concepts that are really clever. One of the first things I discovered is that I do not need to manage memory myself. Continue reading

Rust-01: Why am I learning Rust?

This is a good question, a very good question. Why am I learning Rust? To begin with, I programmed in a lot of languages so far: C++, Python, Swift, Java, Kotlin and TypeScript to name a few. All languages have some features I missed when programming in other languages. Currently, my favorite languages are Kotlin and TypeScript; with Kotlin having the lead. These languages are expressive, and really nice to write. Continue reading

Qt Signals & Slots: How they work

The one thing that confuses the most people in the beginning is the Signal & Slot mechanism of Qt. But it’s actually not that difficult to understand. In general Signals & Slots are used to loosely connect classes. Illustrated by the keyword emit, Signals are used to broadcast a message to all connected Slots. If no Slots are connected, the message “is lost in the wild”. So a connection between Signals & Slots is like a TCP/IP connection with a few exceptions, but this metaphor will help you to get the principle. A Signal is an outgoing port and a Slot is an input only port and a Signal can be connected to multiple Slots.

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Should I use Qt containers or the std ones?

If you come from plain vanilla C++, you only know the C++ Standard Library with its containers like std::vector. If you know how to use them, you can accomplish your tasks pretty fast. But if you’re coming from another language, the naming might be a bit odd. The Qt containers offer both, C++ style and Java style naming of methods. So coming from another language the Qt one’s might be easier to use.

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Why I love the Qt framework

Everyone that knows me, knows that I love the Qt framework. Before I started programming in C++, Java was my primary programming language. I love the generics (yes, some of you will hate me for that opinion right now) and reflection. During my Java-time I used them very often to increase reusability. But while studying we had to learn C++ and I hated it in the beginning. It felt so old and so stiff compared to Java. Continue reading
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