Question

I have a function that contains two for loops, and I’m using a variable called count as the counter. I’ve chosen to recycle the name as the the first loop will finish it’s execution completely before the second one begins, so there is no chance of the counters interfering with each other. The G++ compiler has taken exception to this via the following warning:

error: name lookup of ‘count’ changed for ISO ‘for’ scoping
note: (if you use ‘-fpermissive’ G++ will accept your code)

Is variable recycling considered bad practice in professional software development, or is it a situational concern, and what other implications have I missed here?

Answer 1

Are you doing this?

for(int count = 0; ...)
{
    ...
}

for(count = 0; ...)
{
    ...
}

I doubt gcc would like that, as the second count isn’t in scope. I think it only applies to the first for loop, but gcc has options to accept poor code. If you either make the second int count or move the first to the outer scope, gcc should be happy.

This depends on the circumstances, but I generally don’t reuse variables. The name of the variable should reflect its purpose, and switching part way through a function can be confusing. Declare what you need, let the compiler take care of the optimizations.