Do While Loop

Do-while is a loop that executes one or more times

Syntax

do { // code to execute one or more times } while (condition);

False Condition Example

using System; namespace csharp { class Program { static void Main(string[] args) { int num = 15; do { Console.Write(num + " "); num++; } while (num < 10); } } }

Output:

15

The condition is false but num is printed.

The loop body executes before the condition is checked.

Basically for conditions that are always false, the loop executes once unlike the while cycles which won't execute.

Basic Example

using System; namespace csharp { class Program { static void Main(string[] args) { int num = 0; do { Console.Write(num + " "); num++; } while (num < 10); } } }

Output:

0 1 2 3 4 5 6 7 8 9

The loop executes 10 times (for num from 0 to 9).

The cycle ends when num reaches value of 10.

Infinite loop

Infinite Loop has a condition that's always true.

It can be created due to development mistake or used in advanced algorithm.

Here are examples:

using System; namespace csharp { class Program { static void Main(string[] args) { int num = 0; do { Console.Write(num + " "); } while (num < 10); } } }

Output:

0 0 0 0 0 0 0 0 0 ...

Since num is 0 and never gets modified, the loop repeats infinitely.

using System; namespace csharp { class Program { static void Main(string[] args) { do { Console.Write("1 "); } while (true); } } } 1 1 1 1 1 1 1 1 1 ...

while(true) is a way to specify endless loop.