The structure of the do...while loop is as follow:

do
{
    statements
} while (condition);

As the condition is evaluated after executing the statements, do…while loop is guaranteed to be executed at least once (Docs, 2018).

int x = 10;
do
{
    Console.WriteLine($"Value of x: {x}");
    x++;
} while (x < 20);

Output:

Value of x: 10
Value of x: 11
Value of x: 12
Value of x: 13
Value of x: 14
Value of x: 15
Value of x: 16
Value of x: 17
Value of x: 18
Value of x: 19

Live-code example

References

1. Docs, M. (2018, May 28). do (C# Reference). Retrieved from https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/do