Really? I always do. If you don't, it makes the variable look like a type. It's the same reason why I dislike extra parens around the value in the return statement. Don't make it look like something it isn't.

sizeof is a unary operator and not a function. Only types need to be enclosed in parens. Most people don't know this.

Exactly! For some reason this anti-pattern is very thoroughly entrenched among C programmers and it's so very frustrating.

My other favorite is casting the return value of malloc(), something you see a great deal of and that I always oppose. See http://stackoverflow.com/questions/605845/do-i-cast-the-resu... for my best arguments.

Casting the return value of malloc is necessary in C++. I think that's why it's so widespread, so you can compile your C program with a C++ compiler.