What is a programming structure that repeats a sequence of instructions as long as a specific condition is true?
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The repeat/until loop is a loop that executes a block of statements repeatedly, until a given condition evaluates to true. The condition will be re-evaluated at the end of each iteration of the loop, allowing code inside the loop to affect the condition in order to terminate it. Since the condition is evaluated at the end of each iteration, a repeat/until loop will always be executed at least once, even if the condition is already true when execution arrives at the loop. As an alternative to the repeat/until block loop, the while/do loop will evaluate a condition at the start of each iteration, thus providing a loop that can skip even the first iteration. SyntaxThe basic syntax for a repeat/until loop looks like this: repeat DoSomething(); DoSomethingElse(); until x ≥ 10;where a conditional expression is specified after the closing until keyword, and a list of statements can be provided between the repeat and until keywords. Nullable ConditionsThe condition expression for the repeat/until loop must be of Boolean or Nullable Boolean type. If the condition is a simple boolean, the repeat/until loop will execute as long as the condition evaluates to false (in other words until it is true). If the condition is a Nullable Boolean type, then the additional case of the condition evaluating to nil needs to be considered. While a nil nullable boolean strictly speaking is not equivalent to false, the repeat/until loop treats them the same, and will continue executing the loop if the condition evaluates to either nil or false. Only a value of true will terminate the loop. This behavior symmetrically extends to if/then statements and while/do loops, which also treat a nil condition as equivalent to false. repeat/until Loops and begin/end blocks.Unlike most other statements, and all the other loop types, the repeat/until loop is a block statement, and encloses a list of statements, rather than looping an individual statement. As such, a separate or explicit begin/end block statement is not necessary in order to execute a loop with two or more statements. Prematurely Exiting the Loop or a Loop IterationLike all loops, repeat/until loops can be exited prematurely using the break and exit statements, and a single loop iteration can be cut short by using the continue statement, which jumps to the next loop iteration. See Also
What is a loop structure in programming?A loop in a computer program is an instruction that repeats until a specified condition is reached. In a loop structure, the loop asks a question. If the answer requires action, it is executed. The same question is asked again and again until no further action is required.
What is the term for a sequence of instructions that is repeated until a certain condition is reached?In computer programming, a loop is a sequence of instruction s that is continually repeated until a certain condition is reached. Typically, a certain process is done, such as getting an item of data and changing it, and then some condition is checked such as whether a counter has reached a prescribed number.
Which programming construct is used to repeat programming instructions?Java uses looping constructs to control program flow. When writing programs, certain tasks must be repeated a specific number of times or until a certain condition is met. Loops are programming constructs that simplify just such repetitive tasks.
What is repetition computer programming?Repetition in a program means that lines of code will be run multiple times. Iteration is a term similar to repetition: it means to continue repeating an action until you achieve the correct outcome.
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