WhileB

WhileB is a programming construct found in some older or specialized programming languages, distinct from the more common "while" loop. Its primary characteristic is its execution behavior, which differs subtly from a standard while loop. In a typical while loop, the condition is checked *before* each potential iteration of the loop body. If the condition is false from the outset, the loop body will never execute. In contrast, a whileB construct, often referred to as a "do-while" or "repeat-until" loop in other languages, guarantees that the loop body will execute at least once, regardless of the initial state of the condition. The condition is evaluated *after* the loop body has been executed.

This ensures that any code within the loop's body is performed at least one time before the program checks if it needs to continue looping. This is particularly useful in scenarios where some initialization or a first action must always occur, even if the subsequent conditions for repetition are not met. For example, reading user input and then checking if the input is valid for further processing would benefit from a structure that guarantees at least one read operation. The loop continues to execute as long as the condition remains true (or false, depending on the specific "repeat-until" variant), and terminates when the condition is no longer met. The exact syntax and behavior can vary between languages that implement this construct.