Step-by-Step Programming with Base SAS 9.4, Second Edition, 2nd Edition

Chapter 26

Finding Logic Errors in Your

Program

Finding Logic Errors in Your Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415

Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415

Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415

Using the DATA Step Debugger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416

Basic Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416

How a Debugger Session Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416

Using the Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417

Entering Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417

Working with Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417

Assigning Commands to Function Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417

Using the Macro Facility with the Debugger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418

Using Macros as Debugging Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418

Creating Customized Debugging Commands with Macros . . . . . . . . . . . . . . . . . . 418

Debugging a DATA Step Generated by a Macro . . . . . . . . . . . . . . . . . . . . . . . . . . 418

Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419

Example 1: Debugging a Simple DATA Step When Output Is Missing . . . . . . . . 419

Example 2: Working with Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424

Example 3: Debugging DO Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429

Example 4: Examining Formatted Values of Variables . . . . . . . . . . . . . . . . . . . . . 430

Finding Logic Errors in Your Program

Purpose

The DATA step debugger, which consists of windows and a group of commands, helps

you to interactively identify logic errors, and sometimes data errors, in your SAS

programs. Unlike syntax errors, logic errors do not stop a program from running.

Instead, logic errors cause the program to produce unexpected results. For example, if

you create a DATA step that keeps track of inventory, and your program shows that you

are out of stock but your warehouse is full, you have a logic error in your program.

Prerequisites

Before continuing with this session, you should understand the concepts that are

presented in the following sections:

415