Swift While Loop

Swift Loops

Swift while loop starts by evaluating a single condition. If the condition is true, a series of statements will be run repeatedly until the condition becomes false.

Syntax

The syntax format of the Swift while loop is as follows:

while condition
{
   statement(s)
}

In the syntax,statement(s)can be a statement or a statement block.conditioncan be an expression. If the condition is true, a series of statements will be run repeatedly until the condition becomes false.

The number 0, the string '0' and "", the empty list(), and undefined variables are allfalse, while others are alltrue. To negate true, use the!symbol ornot, which returns false after negation.

Flowchart:

Example

import Cocoa
 
var index = 10

while index < 20 
{
   print( "index 的值为 \(index)")
   index = index + 1
}

The output of the above program execution is:

index 的值为 10
index 的值为 11
index 的值为 12
index 的值为 13
index 的值为 14
index 的值为 15
index 的值为 16
index 的值为 17
index 的值为 18
index 的值为 19

Swift Loops