Question

I usually use a boolean ‘firstTime’ like this:

in C++:

bool firsTime = true;
for (int i = 0; i < v.size(); i++) {
    if (firstTime) {
        //do something just once
        firstTime = false;
    }
    else {
        //do the usual thing
    }
}

in java it would be the same using a boolean instead a bool so I don’t put the code.

The questin is, is there anyway in java or c/c++ to use a bool/boolean in an if clause and automatically assign to that bool/boolean the value false?

I know it seems a nonsense but it would save my code A LOT of lines because I’ve a lot of base cases and in big fors or whiles that is critical.

I do want to know if there is anyway to put a value to false after using it in an if clause. I know that in a for or while we can just use:

if (i == 0)

But I was also thinking in calls to functions that needs to know things and that usually is referenced by bools.

Answer 1

If you don’t have a count already, you can use one instead of a boolean

long counter = 0;
for(String arg: args) {
    if(counter++ == 0) {
       // first
    }
}

An alternative which uses a boolean is

boolean first = true;
for(String arg: args) {
    if(first && !(first = false)) {
       // first
    }
}

---

For sets there is a similar pattern

Set<String> seen = ...
for(String arg: args) {
    if(seen.add(arg)) {
       // first time for this value of arg as its only added once.
    }
}