# About the example programs

## Contents

- Overview
- When you’re typing in
- Errors

## Overview

This section contains example programs written in OPL. The programs are not intended to demonstrate all the features of OPL, but they should give you a few hints. To find out more about a particular command or function, see Keyword Reference. There are some other example programs — see Advanced Topics.

## When you’re typing in

- You can type procedures in all uppercase, all lowercase or any mixture of the two. Be careful with character codes, though — `%A` is different to `%a`.
- When there is more than one command or function on a line, separate each one with a space and colon - for example:

        CLS :PRINT "hello" :GET

However, the colon is optional before a REM statement for example:

        CLS REM Clears the screen

and

        CLS :REM Clears the screen

are both OK.

- Put a space between a command and the arguments which follow it - for example `PRINT a$`. But don’t put a space between a function and the arguments in brackets - for example `CHR$(16)`.
- It doesn’t matter how many spaces or tabs you have at the beginning of a line.

## Errors

The following programs do not include full error handling code. This means that they are shorter and easier to understand, but may fail if, for example, you enter the wrong type of input to a variable.

If you want to develop other programs from these example programs, it is recommended that you add some error handling code to them. See Error Handling for further details.