Archive for the ‘C/C++’ Category

Idiomatic C/C++: Avoiding Assignment Vs. Equality Errors

Thursday, October 25th, 2007

This is a bit of idiomatic c/c++, that is to say that this isn’t part of any standard, it is just “the way things are done” in c/c++. Ever made an error in a conditional using the assignment operator (=) instead of the equality operator (==)? I know I have, but not so much anymore. The trick is that when you are comparing a variable to a constant to put the constant first. This way if you mess up you will get a compiler error stating that you can’t assign to a constant. This is much preferable to a potentially subtle bug that will no doubt bite you when a deadline is looming. So instead of:

int x;
if( x == 5)
    ; //Do something


int x;
if( 5 == x)
    ;//Do something