This isn’t exactly confined to C, in fact it applies to many programming languages where braces or curly brackets {like this} are optional after an if. It even applies to Pascal with Begin ends which are optional after an if.

You can have the first or the second as shown below.

if (expressions) 
  DoSomething;

if (expression {
  DoSomething;
}

I saw a recent example where the DoSomething was a logging expression which the compiler optimised away so the if, which lacked braces applied to the next statement. As the if was only true on rare occasions. It meant that that statement which should have been run every time was only run on those rare occasions.

So the prevailing wisdom and one that I entirely agree with is that you should always use braces. If you don’t you risk accidentally introducing bugs like this.

Note. that link is to a discussion on the C programming Subreddit (on Reddit.com).

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