How to Loop Again in for Loop in Swift

In programming, loops are used to repeat a block of lawmaking. For example, if you want to show a message 100 times, then you lot can use a loop. Information technology's just a simple case, you tin achieve much more than with loops.

In the previous tutorial, y'all learned well-nigh the Swift for-in Loop. Here, you are going to learn almost while and repeat...while loops.

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Swift while Loop

Swift while loop is used to run a specific code until a certain condition is met.

The syntax of while loop is:

          while (condition){   // body of loop }        

Here,

• A while loop evaluates condition inside the parenthesis ().
• If condition evaluates to true, the code within the while loop is executed.
• condition is evaluated once again.
• This process continues until the status is false.
• When condition evaluates to faux, the loop stops.

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Flowchart of while Loop

Working of Swift while Loop

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Example ane: Swift while Loop

          // program to display numbers from ane to 5  // initialize the variable var i = one, north = 5  // while loop from i = one to 5 while (i <= n) {   print(i)    i = i + 1 }        

Output

          1 2 3 iv five        

Here'due south how the plan works.

Variable	Condition: i <= northward	Action
i = 1 due north = 5	truthful	1 is printed. i is increased to 2.
i = 2 n = 5	truthful	2 is printed. i is increased to 3.
i = iii n = 5	truthful	iii is printed. i is increased to 4.
i = 4 n = 5	true	iv is printed. i is increased to 5.
i = 5 n = five	true	five is printed. i is increased to 6.
i = 6 n = 5	fake	The loop is terminated.

Example 2: while Loop to Brandish Game Level

          var currentLevel:Int = 0, finalLevel:Int = 5 let gameCompleted = true while (currentLevel <= finalLevel) {    if gameCompleted {     print("You have passed level \(currentLevel)")       currentLevel += 1   } } impress("Level Ends")        

Output

          Y'all have passed level 0                                                                                                                  You have passed level 1                                                                                                                  Yous take passed level two                                                                                                                  You take passed level three                                                                                                                  Yous accept passed level 4                                                                                                                  You take passed level 5                                                                                                                  Level Ends                  

In the to a higher place example, we have used a while loop to cheque the current level and display it on the panel.

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repeat...while Loop

The echo...while loop is like to while loop with one central difference. The body of repeat...while loop is executed one time before the test expression is checked.

The syntax of repeat..while loop is:

          repeat {   // trunk of loop } while (condition)        

Here,

• The body of the loop is executed at get-go. Then condition is evaluated.
• If condition evaluates to true, the body of the loop inside the repeat statement is executed again.
• status is evaluated in one case once again.
• This process continues until condition evaluates to false. And so the loop stops.

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Flowchart of repeat...while Loop

Working of repeat...while Loop in Swift

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Case three: repeat...while Loop

          // program to display numbers  var i = i, north = 5  // echo...while loop from 1 to 5 echo {      print(i)    i = i + 1  } while (i <= n)        

In the above instance, initially the value of i = 1 and n = 5. For the first time the statement inside the loop executes without checking the status. The condition is checked after the first iteration is consummate.

Hither's how this programme works,

Variable	Status: i <= n	Activeness
i = 1 northward = five	non checked	1 is printed. i is increased to 2.
i = 2 north = 5	true	2 is printed. i is increased to 3.
i = iii n = 5	true	3 is printed. i is increased to 4.
i = 4 n = v	true	4 is printed. i is increased to 5.
i = five north = 5	true	5 is printed. i is increased to 6.
i = half dozen north = 5	faux	The loop is terminated.

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Infinite while Loop

If the condition of a while loop is always true, the loop runs for infinite times (until the retentivity is full). This is called infinite while loop. For example,

          while (true) {     print("Endless Loop") }        

Output

          Endless Loop Endless Loop  . . .        

Here, the status is always true. Hence, the while loop will run for space times.

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for vs while loop

A for-in loop is ordinarily used when the number of iterations is known. For example,

          // this loop is iterated 5 times for number in i...5 {    // trunk of loop }        

Nevertheless, a while loop is ordinarily used when the number of iterations are unknown. For example,

          while (status) {     // body of loop }        

Notation: The working of echo...while is the same as the while. Hence, information technology is besides used when the number of iterations is unknown.

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Source: https://www.programiz.com/swift-programming/repeat-while-loop

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