Automating Repetitive Tasks - Using Loops

If you want to repeat several instructions in a procedure, you can use a loop. Loops often are used in programming because they condense many lines of instructions into a group that can be run more than once. Loops make your procedures more concise, and with a loop, you can continue asking a user for input until the correct answer is given.

With loops, you can keep adding or subtracting numbers until you want to stop. You can define how many times you want a procedure to handle an operation. You will see how to use simple loops to repeat instructions in a procedure.

The two types of loops you may find useful are repetitive loopsReference and conditional loops.Reference Loops begin with a DO instruction and end with the END instruction. The following is a list of topics in this section:

DO num loopReference

Repeats the loop a fixed number of times.
DO i=1 to 10 loopReference
Numbers each pass through the loop. Sets a starting and ending value for the variable.
DO WHILEReference
Tests for true or false at the top of the loop. Repeats the loop if true. If false, continues processing after END.
Do UNTILReference
Tests for true or false at the bottom of the loop. Repeats the loop if false. If true, continues processing after END.
LEAVEReference
Causes the interpreter to exit a loop.
DO FOREVER Reference
Repeats instructions until the user says to quit.
Getting out of loopsReference
Requires that you press the Ctrl+Break keys.
Parsing wordsReference
Assigns a different variable to each word in a group.

---

[Back: The Logical Operators, NOT, AND, OR]
[Next: Repetitive Loops]