WHILE...WEND

Syntax

WHILE <expression>
[<loop statements>]
WEND

Purpose

To execute a series of statements in a loop as long as a given condition is true.

Remarks

If <expression> is not zero (i.e., true), <loop statements> are executed until the WEND statement is encountered. BASIC then returns to the WHILE statement and checks <expression>. If it is still true, the process is repeated. If it is not true, execution resumes with the statement following the WEND statement.

WHILE/WEND loops may be nested to any level. Each WEND will match the most recent WHILE. An unmatched WHILE statement causes a "WHILE without WEND" error, and an unmatched WEND statement causes a "WEND without WHILE" error.

Example

90 REM BUBBLE SORT ARRAY A$
100 FLIPS = 1   ' Force one pass through loop
110 WHILE FLIPS
115   FLIPS = 0
120   FOR I = 1 TO J - 1
130     IF A$(I) > A$(I+1) THEN SWAP A$(I), A$(I+1): FLIPS = 1
140   NEXT I
150 WEND

This example shows a bubble sort algorithm using WHILE/WEND. The loop continues as long as FLIPS is non-zero, indicating that swaps were made in the last pass.

See Also

• FOR...NEXT - Execute statements repeatedly with a loop counter
• GOSUB...RETURN - Branch to and return from a subroutine
• GOTO - Branch unconditionally to a specified line number
• IF...THEN...ELSE - Make decisions and control program flow based on conditional expressions
• ON...GOSUB/ON...GOTO - Branch to one of several line numbers based on an expression value