DoStatement

DoStatement is a control flow construct used in many imperative programming languages to repeat a block of code. Its key characteristic is that the block is executed first, and only then is a condition evaluated to determine whether the block should be executed again. This guarantees that the body of the statement runs at least once.

In languages such as C, C++, Java, and C#, the common syntax is a do-while loop: do { /* statements */ } while (condition); The body is executed, and then the condition is tested; if the condition is true, the body runs again. This form is often used when the loop body must run to obtain or process initial input before a decision about continuation can be made.

Other languages implement similar ideas with different syntax or terminology. Visual Basic, for example, provides Do...Loop constructs that can test the condition at the end or the beginning, yielding a do-while-like behavior but with different explicit forms. Some languages and language grammars describe the construct as a DoStatement or a do-while statement to reflect its behavior, rather than a generic while loop.

Common semantics include the possibility of at least one execution, the potential use of break or continue statements inside the loop to alter flow, and the fact that side effects within the body may influence the continuation condition. DoStatement is frequently used for input loops, initialization that requires one pass, or situations where the loop must perform an action before deciding whether to repeat.

In program analysis and compiler design, DoStatement is often represented as a distinct node in an abstract syntax tree (AST) to capture its unique ordering of body execution prior to condition evaluation.