REPEAT-UNTIL allows us to create a repetitive code loop, which REPEATs a block of code UNTIL a specific conditional expression evaluates to TRUE. In that sense, REPEAT-UNTIL defines a block of code, operating somewhat like the BEGIN-END compound statement structure that we covered in Chapter 6, Introduction to C/SIDE and C/AL. REPEAT tells the system to keep reprocessing the block of code, while the UNTIL serves as the exit doorman, checking if the conditions for ending the processing are true. Because the exit condition is not evaluated until the end of the loop, a REPEAT-UNTIL structure will always process at least once through the contained code.

REPEAT-UNTIL is very important in NAV because it is often part of the data input cycle along with the FIND-NEXT structure, which will be covered shortly.

Here is an example of the REPEAT-UNTIL structure to process and sum data in the 10-element array CustSales:

LoopCount := 0; 
REPEAT 
LoopCount := LoopCount + 1; 
TotCustSales := TotCustSales + CustSales[LoopCount]; 
UNTIL LoopCount = 10;