1

The following code is in my Swift lesson:

var password = "1"

while true {

//Execute some code here
}

My question is about the second line of code. It doesn't provide a condition before the true value. Is that allowed? Isn't this invalid syntax since it has no condition to check for true value? Aren't I supposed to state what condition to check for??

2

true is a boolean expression and while wants just that - boolean expression. You can of course do this:

while true == true {

and also

while true == (true == true) { ...

but that's just silly, "while true" is enough.

"while true { ... }" is an infinite loop that will loop "forever" unless you put some break / return / throw statement inside the loop.

while true {
    if someCondition { break }
}
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3

In this case, true is literally the "condition".

For what it's worth, I've been programming for over a decade and a half and still think while true looks nonsensical, despite its ubiquity. A repeat statement without the following while would be much easier to understand.

3 Likes
4

Indeed, and I was not even sure if repeat statement without a while is valid Swift or not - checked just now. It is not... Perhaps it should be?

2 Likes
5

Okay, got it, thank you! (The true being an expression part is a suprise! I'm learning.)

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6

Found the idea of "repeat" without "while" was already suggested, discussed and rejected 6 years ago.

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8

In other languages about a third is for "loop" another third for "while true" / while 1". "Loop" looks somewhat nicer but it doesn't look realistic to add it to Swift at this point.