Skip to main content

Not or Bang versus Equals False

I generally write code in C#. There are 2 mains ways that I have seen to check if a Boolean expression returns in the negative.

Using a bang to symbolize "Not" before the expression


And checking if the expression equals false

(expression) == false

I have gone back and forth between using both never really having a strong feeling as to which I prefer.

Today I have decided that I believe one is better than the other.

I came to this conclusion by really thinking about the Principle of least surprise. The principle when applied to coding is that you want your code to not surprise the next developer. What can you do to make your code easy to follow and understand?

Viewing these 2 options under the lens of the Principle of least surprise, I think one is clearly more surprising than the other. I think that using the bang before an expression is much more surprising than equating the expression to false. The little exclamation point can get lost while reading code, especially complex code. 

Now I will use equals false going forward to make my code as unsurprising as I can.


  1. I actually prefer a third option which is. To replace the entire Boolean expression with a variable named "isSomething" then using ! or == false should be irrelevant to the person reading the code. Of course you could also argue that within you assignment to the "is" variable you should be using == false instead of !. Good post.

    1. Thank you for the feedback. I agree that is a good way to make this even clearer to the next developer, and as you mentioned I believe in many cases these would be used together.


Post a Comment

Popular posts from this blog

Converting a Large AngularJS Application to TypeScript Part 1

I work on a project that uses AngularJS heavily. Recently we wondered if using a preprocesser like CoffeeScript or TypeScript for our JavaScript would be beneficial. If our team is going to switch languages, we would need to be able to convert existing code over without much pain and we would have to find enough value in switching that it would be worth the conversion.

I had read an article that stated that because TypeScript is a SuperSet of JavaScript, you could convert a plain JavaScript file to TypeScript by changing the extension to .ts and not much else would need to change. I wanted to test out this claim, so I took a file that I was familiar with, an Angular Controller, and tried to convert it to TypeScript to see how much effort it would take and then try to figure out where we would benefit from using TypeScript.

This is what the controller JavaScript file looked like to start out with:
(function () { 'use strict'; angular .module('app') …

Converting a Large AngularJS Application to TypeScript Part 2

In part 1 I was able to take an Angular controller written in JavaScript and convert it to a TypeScript file while doing very little to change the code. In this post I am going to explore transitioning that same controller to actually use the features provided in TypeScript. This is how I left off my controller:
declare var angular: any; (function () { 'use strict'; var controller: any = function($scope){ ... } angular .module('app') .controller('controller', controller); controller.$inject = ["$scope"]; })();
While performing the translation from JavaScript to TypeScript, I would make sure at every step that the functionality I expected still worked, so if anything I did broke the system I would change it back and try again with another approach. Also if something seemed like it worked too easily, I would break it on purpose to make sure I wasn't getting a false result through browser caching a previously working fil…

Gamify TDD

I like it when things that would not normally be associated with games add concepts from games as a way to incentives you to accomplish things. Why simply go for a run if you can have an app that will track you and give you a gold star if you do better than you did the last time? Why go to the coffee shop that only gives you coffee if the other one will give you points that you can redeem for free drinks eventually?

I was recently introduced to CodeSchool, an online training system similar to PluralSight, it has video courses and challenges you can take to prove that you retained what the video taught. CodeSchool also adds badges and tracks to your learning, so as you complete a video and its challenges you get a badge. Complete a collection of courses within a specific discipline and you become a master of that discipline.

Some of these incentives are not tangible and really don't mean much in the real world, but they tend to work for me. If I start working towards a large goal a…