Choose a branch and repeat an action

Silex conditions are always bool values. They can select a branch with if, control a while loop, or filter iterations in a for loop.

Choose a branch

func main() {
    let value = 0

    if value < 0 {
        print("negative")
    } elif value == 0 {
        print("zero")
    } else {
        print("positive")
    }
}

else if is another accepted spelling of elif. The first true condition selects its branch; else handles the remaining case.

Repeat while a condition is true

var remaining = 3

while remaining > 0 {
    print(remaining)
    remaining--
}

The condition is evaluated again before every iteration. A condition that is false from the start never executes the body.

Stop or skip an iteration

break exits the nearest loop. continue abandons only the current iteration and resumes at the next test of that same loop.

while ready() {
    if finished() {
        break
    }
    if ignored() {
        continue
    }
    work()
}

Iterate over an integer range

for index in 0...3 {
    print(index)
}

for index in range(3, 0) {
    print(index)
}

Both forms exclude the end bound. 0...3 produces 0, 1, then 2; range(3, 0) produces 3, 2, then 1. Equal bounds produce no iteration.

To traverse a collection, see the iteration forms.

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