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first checks whether x is less than 5, which it is, so then the {loop body} is entered, where the printf function is run and x is incremented by 1. After completing all the statements in the loop body, the condition, (x < 5), is checked again, and the loop is executed again, this process repeating until the variable x has the value 5.
The loop counter is used to decide when the loop should terminate and for the program flow to continue to the next instruction after the loop. A common identifier naming convention is for the loop counter to use the variable names i , j , and k (and so on if needed), where i would be the most outer loop, j the next inner loop, etc.
However, infinite loops can sometimes be used purposely, often with an exit from the loop built into the loop implementation for every computer language, but many share the same basic structure and/or concept. The While loop and the For loop are the two most common types of conditional loops in most programming languages.
Do While condition instructions Loop or Do Until notcondition instructions Loop or While condition instructions Wend (Visual Basic .NET uses End While instead) Do instructions Loop While condition or Do instructions Loop Until notcondition: i must be declared beforehand. For i = first To last «Step 1» instructions Next i. For Each item In set
In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the do-while loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program.
A possible variant is to allow more than one while test; within the loop, but the use of exitwhen (see next section) appears to cover this case better. In Ada, the above loop construct (loop-while-repeat) can be represented using a standard infinite loop (loop - end loop) that has an exit when clause in the middle (not to be confused with the ...
Examples are if, while, const, for and goto, which are keywords that happen to be common to both languages. In C, the basic built-in type names are also keywords (e.g., int , char ) or combinations of keywords (e.g., unsigned char ), while in Pascal the built-in type names are predefined normal identifiers.
condition-controlled loop with test at start of loop: Algol 60: for index := expression while test do <statement> ; Pascal: while test do < statement >; C, Java: while (test) < statement >; Ada: while test loop < sequence > end loop; Fortran 90: