File Name: difference between while and do while .zip
Previously you have learned about while loop and do while loop in C. Now, we will see the basic difference between while and do while with example. The while loop is pre-test loop , where firstly the condition is checked and if the condition is true then only the statements of the while loop execute.
Loops in C++
These statements are commonly called loops. Here, the main difference between a while loop and do while loop is that while loop check condition before iteration of the loop. On the other hand, the do-while loop verifies the condition after the execution of the statements inside the loop. Furthermore, the while loop is known as the entry-controlled loop. Conversely, the do while loop is called the exit controlled loop.
In 'do-while' loop the controlling condition appears at the end of the loop. Iterations The iterations do not occur if, the condition at the first iteration, appears false. The iteration occurs at least once even if the condition is false at the first iteration.
Alternate name Entry-controlled loop Exit-controlled loop Semi-colon Not used Used at the end of the loop. The while loop first verifies the condition, and if the condition is true, then, it iterates the loop till the condition turns out false. The condition in while loop can be any boolean expression. If the condition becomes true, then loop iterates itself, and if the condition becomes false, then the control passes to the next line of the code immediately followed by the loop.
The statements or the body of the loop can either be an empty statement or a single statement or a block of statements. In the example below the code will print from 1 to This continues until the condition is true, as soon as the condition becomes false, the loop is terminated.
Like for loop, the while loop also first checks the condition and then execute the loop body. As in the while loop, if the controlling condition becomes false in the first iteration only, then the body of the while loop is not executed at all. But the do-while loop is somewhat different from while loop.
The do-while loop executes the body of the loop at least once even if the condition is false at the first attempt. In a do-while loop, the body of loop occurs before the controlling condition, and the conditional statement is at the bottom of the loop. The condition here is also a boolean expression, which is true for all non-zero value.
In a do-while loop, the control first reaches to the statement in the body of a do-while loop. The statements in the body get executed first, and then the control reaches the condition part of the loop.
The condition is verified and, if it is true, the loop is iterated again, and if the condition is false, then the control resumes to the next line immediately after the loop. Both while and do-while loop are the iteration statement, if we want that first, the condition should be verified, and then the statements inside the loop must execute, then the while loop is used.
If you want to test the termination condition at the end of the loop, then the do-while loop is used. I loved this page very nicely presented and easy answers with key points covered in it……. Your email address will not be published. Key Differences Between while and do-while Loop The while loop checks the condition at the starting of the loop and if the condition is satisfied statement inside the loop, is executed. As against, in the do-while loop, the condition is checked after the execution of all statements in the body of the loop.
If the condition in a while loop is false, not a single statement inside the loop is executed. The while loop is also known as the entry-controlled and pre-checking loop because in this loop, the body of the loop is executed prior to checking the condition. Conversely, the alternate name for the do-while loop is the exit-controlled and post-checking loop, the reason behind this is that the checking of the loop condition is followed by the execution of the body of the loop.
The syntax of a do-while loop includes a semi-colon to terminate the loop. On the contrary, there is no use of the semi-colon in the while loop syntax. Comments I loved this page very nicely presented and easy answers with key points covered in it……. Pascal is more clean and clear: Repeat …. This is how the understanding of loops should be taught!!!!!! Leave a Reply Cancel reply Your email address will not be published. The iterations do not occur if, the condition at the first iteration, appears false.
C while and do...while Loop
Loops are one of the basic building blocks for creating programs. There are times when we wish to execute the statements more than once, in which case loops are used. A loop is a sequence of instruction that iterates a statement based on certain conditions and then executes block or blocks of code repeatedly until the condition is satisfied. A loop allows us to write short pieces of code that runs multiple times rather than writing one long set of instructions to accomplish a task. Loop helps run a shorter piece of instruction a number of times, which gives your program greater versatility in working in the real world.
Do while loop
In this tutorial you will learn how to repeat a series of actions using loops in PHP. Loops are used to execute the same block of code again and again, as long as a certain condition is met. The basic idea behind a loop is to automate the repetitive tasks within a program to save the time and effort. PHP supports four different types of loops. You will also learn how to loop through the values of array using foreach loop at the end of this chapter.
These statements are commonly called loops. Here, the main difference between a while loop and do while loop is that while loop check condition before iteration of the loop. On the other hand, the do-while loop verifies the condition after the execution of the statements inside the loop.
How to begin Get the book. Practice problems Quizzes. Being able to have your program repeatedly execute a block of code is one of the most basic but useful tasks in programming -- many programs or websites that produce extremely complex output such as a message board are really only executing a single task many times. They may be executing a small number of tasks, but in principle, to produce a list of messages only requires repeating the operation of reading in some data and displaying it.
In most computer programming languages, a while loop is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. The while loop can be thought of as a repeating if statement. Note that it is possible, and in some cases desirable, for the condition to always evaluate to true, creating an infinite loop.
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A Loop executes the sequence of statements many times until the stated condition becomes false. A loop consists of two parts, a body of a loop and a control statement. The control statement is a combination of some conditions that direct the body of the loop to execute until the specified condition becomes false. The purpose of the loop is to repeat the same code a number of times. Types of Loops in C Depending upon the position of a control statement in a program, looping in C is classified into two types: 1. Entry controlled loop 2.
In this tutorial, you will learn to create while and do In the previous tutorial, we learned about for loop. In this tutorial, we will learn about while and do.. To learn more about test expression when the test expression is evaluated to true and false , check out relational and logical operators.
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