C# do while loop
In this chapter you will learn:
- What is do while loop
- How to create do while loop
- Example for do while loop
- Example to do calculation in a do while loop
- Using break to exit a do-while loop
- How to use do while loop to find the square root of a number
- Do / while loop with a console read
Description
do-while loops test the
expression after the statement block has executed ensuring that the block is always
executed at least once.
Syntax
do while loop has the following syntax.
do{
statements;
}while(conditions);
Example
We can change the while loop to do while loop.
using System;//w w w. j a va2s. c om
class Program
{
static void Main(string[] args)
{
int i = 5;
do
{
Console.WriteLine(i);
i--;
} while (i > 0);
}
}
The output:
Example 2
The following code
displays the digits of an integer in reverse order with do...while loop.
using System; // w ww.ja v a2 s.c o m
class MainClass {
public static void Main() {
int num;
int nextdigit;
num = 198;
Console.WriteLine("Number: " + num);
Console.Write("Number in reverse order: ");
do {
nextdigit = num % 10;
Console.Write(nextdigit);
num = num / 10;
} while(num > 0);
Console.WriteLine();
}
}
The code above generates the following result.
Example 3
Using break to exit a do-while loop
using System; /* w w w. j av a2s . co m*/
class MainClass {
public static void Main() {
int i;
i = -10;
do {
if(i > 0)
break;
Console.Write(i + " ");
i++;
} while(i <= 10);
Console.WriteLine("Done");
}
}
The code above generates the following result.
Example 4
The following code uses the do while statement to implement Newton's method for finding the square root of a number.
using System;// w ww . j av a2 s. c om
public class MainClass {
public static void Main( ) {
double epsilon = 1.0e-9;
double guess = 11.0;
double result = 0.0;
double value = 2;
result = ((value / guess) + guess) / 2;
do {
Console.WriteLine( "Guess Value = {0}", guess );
Console.WriteLine( "Result Value = {0}", result );
guess = result;
result = ((value / guess) + guess) / 2;
} while( Math.Abs(result - guess) > epsilon );
Console.WriteLine("The approx sqrt of {0} is {1}", value, result );
}
}
The code above generates the following result.
Example 5
Do / while loop with a console read
using System;/*w w w . j av a 2 s . c om*/
using System.IO;
class MainClass
{
public static void Main(string[] args)
{
string ans;
do
{
Console.Write("Are you done? [yes] [no] : ");
ans = Console.ReadLine();
}while(ans != "yes");
}
}
The code above generates the following result.
Next chapter...
What you will learn in the next chapter:
- C# for loops
- Syntax of for loop
- Example of for loop
- Example for nested for loop
- Control variabls in for loop
- Omit for loop part