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Loops in C are divided into two areas. A person is the loop system, and the other is the management assertion. Each loop is exclusive in its way. Do though loop is alike to a when loop in some factors. In this loop, for starters, all the statements inside the physique are executed. In scenario the condition is true, then the loop is again executed until finally the issue turns into wrong. In this guideline, we will lose some gentle on the illustrations of do-though loops.



although (expression)

Illustration 1

In this instance of the do-although loop, we want to calculate the sum of the figures. This can be finished in two means. Both the values are released in the software by your self or ask the consumer to enter the values and then calculate the sum. Like for loop, we will also supply a restrict up to which the figures are to be entered. But in the for loop, we applied to enter the frequent quantity to start off the loop easily and end at that variety. If we want to implement a certain problem that may perhaps not be constant, the do-whilst loop is utilized in this condition. So in this case in point, we have applied a though ailment to go on entering the values until eventually the consumer enters .. The loop’s human body will present the information to enter the number, and then the sum is calculated. Following the loop system, the issue is utilized in the variety of a while statement.

Printf(“Enter a variety:)
Scanf(%lf”, &number)
Sum += amount

Though(range != .)

The exclamation mark is used to negate the problem.

If we want to watch the output of the previously mentioned code, then we will use the next appended commands. In the Ubuntu procedure, this output acquiring process is accomplished through the Ubuntu terminal.

The code compiler used in Linux for C is GCC. This will initial compile the code, and then we will get the output.

$ GCC –o file3 file3.c
$ ./file3

By observing the output, you will see that the procedure prompts the concept of “Enter a number” until the consumer has entered that value provided in the condition that is .. Right after that, the sum is calculated and is displayed in the future line.

Example 2

Now, relocating towards another example. This instance will use the do-though loop to estimate the multiples of a provided amount. But this time, the values are not needed from the consumer. Other than, only the original benefit is described, and this worth is incremented in every loop execution.

In the preceding illustration, each and every benefit was entered by the consumer. Whereas in this circumstance, there is no involvement of the person.

Printf(%d/n” , 5*num)


In this program, the condition is to increment to the number that must be less or equal to 7. It means the loop will execute 7 times, and we will get the result in 7 numbers. The initial value is 1 after one loop, it will be incremented and will become 2 and so on for further increments.

In comparison with the body of the do-while loop, for loop has increment statement inside the definition, whereas, while/ do-while loop has this statement inside the do-while body.

Moving to get the output, the same compilation and execution method will be used.

You can see that the result shows all the multiples of 5 up to the 7th number as the number is 5 in the formula.

Example 3

This is another illustration of the do-while loop. Similar to the previous example, interest will be calculated in this example. This is an example of daily life. Different values do interest calculation. The user will provide all these values at the run time when we execute the program. The value is stored in the variable. Hence the variable will be used in the formula as we cannot use the values/ numbers directly in the calculations if provided by the user.

Printf=(“interest rate= %.5f, (a*b*c)/100)

This line shows the calculations in the loop body. After the loop body is closed. While the statement is define

This is the condition that shows that the system will continue requiring the number from the user until the user press the character y. this “y” stands for yes. When all values are given, and the interest is also calculated, the next line user will be asked whether he wants the system for again calculation or want to quit. So if the user presses y, it will continue. Otherwise, in the second condition, the loop will not execute.

The output is shown below in the cited image. GCC compiler, after compilation, executes the program, and the result is shown in the display.

The output shows that firstly, the user has pressed y so that the program will run again. When ‘n’ is pressed, the code will stop execution.

The dissimilarity between while loop and do-while loop.

The basic difference in both the loops is that in the while loop, the while statement is defined above the loop body, whereas in the do-while, the while statement is declared after the loop body.

To understand the difference in both the loops, we will shed some light on the given an example. As these are two loops, so we will consider two programs so that their separate working will make it easy to discriminate.

While loop

In the first program, we have used the while loop. In while loop declaration, it is initiated before the loop body. In this example, we print two lines, one inside the loop body and outside. The condition is that the loop will carry on till the variable value reaches 1, whereas this value was mention as 0 at the start.


This condition will be true if the value is incremented. So it will reach 1 from 0. But as there is no value incrementation inside the loop body. The value will remain the same, that is 0. That’s why the loop will not run.

Do while loop

The concept is the same two lines are to be printed just like the above example. The variable is also initiated as 0. At the same time, the condition is true until it reaches 1.

while ( i ==1)

The output method is the same. While seeing the output, first consider the while loop. This shows the line that was printed outside the loop is displayed, and the inside is not. This is because the condition is false.

Considering the do-while loop result, you can see that both the lines are displayed. This is because the do-while loop is executed at least once, even if its condition is false. In contrast, the condition is written and evaluated after the “do” loop is executed.


In this guide, we have discussed the dissimilarity between the while and do-while loop and their working. The functionality of the do-while loop is discussed in a detailed way through examples.

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