Delphi in a Nutshell

Name

Goto Keyword

Syntax

goto Label

Description

The goto statement transfers control to the given label. The label can be any identifier or a digit string with up to four digits. You cannot use an identifier used as a label as a local variable in the same block.

Tips and Tricks

• Indiscriminate use of the goto statement results in the classic problem of “spaghetti” code, that is, source code that is as tangled as a plate of spaghetti.

• The most common use for the goto statement is to jump out of deeply nested loops. When it is used in this way, you can think of it as a super-Break statement.

• The entire VCL source code contains only two goto statements. Both are used to break out of a nested loop. Consider this a guideline for the proper use of the goto statement.

• Jumping from outside a block (loop, conditional, or nested subroutine) into the block has unpredictable results. Delphi does not permit a jump into or out of any part of a try-except or try-finally statement.

• Unlike standard Pascal, Delphi does not permit a jump from a nested subroutine into an outer subroutine. Use the Exit procedure to return prematurely from a function or procedure.

Example

// Find the first non-blank cell in a grid, and return its // contents, converted to all uppercase. If the entire grid // is blank, return a default string. Skip over the fixed // rows and columns because they are just identifying headers. procedure UpcaseCell(Grid: TStringGrid; const Default: string): string; var R, C: Integer; label NestedBreak; ...