This question is inspired by this question, which features the following code snippet. int s; if((s = foo()) == ERROR) print_error(); I find this style hard to read and prone to error (as the original question demonstrates -- it was prompted by missing parentheses around the assignment). I would instead write the following, which is actually shorter in terms of characters. int s = foo(); if(s == ERROR) print_error(); This is not the first time I've seen this idiom though, and I'm guessing there are reasons (perhaps historical) for it being so often used. What are those reasons?