Loop
Loop¶
A loop is a sequence of instruction(s) that is continually repeated until a certain condition is reached.
An infinite loop is one that lacks a functioning exit routine.
The result is that the loop repeats continually until the operating system senses it and terminates the program with an error or until some other event occurs.
Types of Loops¶
- Entry Controlled Loop - In an entry controlled Loop, the control statement is written right at the beginning of the Loop. - This type of Loop is also called a pre-checking Loop. The conditions in the control statements are checked at first, and only if the conditions are true, the body of the Loop is executed. - If the condition turns out to be false, the lines of code in the body of the Loop will not be executed.
- Exit Controlled Loop - In an exit controlled Loop, The control statement is written at the end of the Loop structure. - The lines of codes in the body of the Loop are executed once before the condition is checked. Hence, this type of Loop is also called a post-checking Loop.
| # | Loop Type | Description |
|---|---|---|
| 1 | While Loop | In while loop, a condition is evaluated before processing a body of the loop. If a condition is true then and only then the body of a loop is executed. |
| 2 | Do-While Loop | In a do…while loop, the condition is always executed after the body of a loop. It is also called an exit-controlled loop. |
| 3 | For...Loop | In a for loop, the initial value is performed only once, then the condition tests and compares the counter to a fixed value after each iteration, stopping the for loop when false is returned. |