|
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 ]. ==Overview== The ''while'' construct consists of a block of code and a condition/expression.〔http://docs.oracle.com/javase/tutorial/java/nutsandbolts/while.html〕〔https://www.tutorialcup.com/cplusplus/while-loop.htm〕 The condition/expression is evaluated, and if the condition/expression is true, the code within the block is executed. This repeats until the condition/expression becomes false. Because the ''while'' loop checks the condition/expression before the block is executed, the control structure is often also known as a pre-test loop. Compare this with the ''do while'' loop, which tests the condition/expression ''after'' the loop has executed. For example, in the C programming language (as well as Java, C#, Objective-C, and C++, which use the same syntax in this case), the code fragment int x = 0; while (x < 5) first checks whether x is less than 5, which it is, so then the 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. Note that it is possible, and in some cases desirable, for the condition to ''always'' evaluate to true, creating an infinite loop. When such a loop is created intentionally, there is usually another control structure (such as a break statement) that controls termination of the loop. For example: while (true) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「While loop」の詳細全文を読む スポンサード リンク
|