Now that you're familiar with the basics, you can learn how to use the SAS programming windows to edit and debug programs effectively.

In this chapter you learn to

File shortcuts are available in the SAS Explorer window. To include a program using file shortcuts:

The file opens in a new code editing window, with the file name shown as the window title.

To view and manage any files in your operating environment, you can use the My Favorite Folders window.

To include a file that is stored in My Favorite Folders:

The file opens in a new code editing window, with the file name shown as the window title.

To use the Open window:

The file opens in a new code editing window, with the file name shown as the window title.

If you're not sure of the name of the file in which your program is stored, you can do either of the following:

To resume your SAS session after issuing the X command, issue the appropriate host system command, as shown below.

You can also include a program by issuing an INCLUDE command.

Suppose you want to include the program D:ProgramsSasMyprog1.sas in the Windows operating environment. To do so, you can issue the following INCLUDE command:

include 'd:programssasmyprog1.sas'

Because this is a command (not a SAS statement), no semicolon is used at the end.

Remember that SAS programs consist of SAS statements. Take a look at the SAS program that is shown in a code editing window below.

Although you can write SAS statements in almost any format, a consistent layout enhances readability and helps you understand the program's purpose. It's a good idea to

data work.bankacct;
   infile records;

      input Name $ 1-10 AccountType $ 12-20
            Deposit 22-25 Withdrawal 27-30;
run;
proc print data=work.bankacct;
  run;
proc means mean;
   var deposit withdrawal;
run;

Now let's look at the Enhanced Editor window features that you can use to edit your SAS programs.

When you edit SAS programs in the Enhanced Editor, you can take advantage of a number of useful features. The following section shows you how to

You can also

The Enhanced Editor uses visual aides such as color coding and code sections to help you write and debug your SAS programs.

You can use the margin on the left side of the Editor window to

To find text in the Editor window, select Edit

You can define a character string so that when you type it and then press the Tab key or the Enter key, the string expands to a longer character string.

For example, you could define the abbreviation myv7sasfiles, which would expand to 'c:winntprofilesmyidpersonalmysasfilesv7';. Abbreviations are actually macros that insert one or more lines of text.

To create an abbreviation,

To use an abbreviation, type the abbreviation. When an abbreviation is recognized, a tooltip displays the expanded text. Press the Tab key or Enter key to accept the abbreviation.

You can modify or delete abbreviations that you create.

When you use the Enhanced Editor, you can see different parts of the same file simultaneously by opening multiple views of the same file. While you are working with multiple views, you are working with only one file, not multiple copies of the same file.

To open multiple views of the same file,

The filename in the title bar is appended with a colon and a view number. For example, in the illustration above, the file names are vansales.sas:1 and vansales.sas:2.

Changes that you make to a file in one view, such as changing text or bookmarking a line, occur in all views simultaneously. Actions such as scroll bar movement, text selection, and expanding or contracting a section of code occur only in the active window.

You can customize the Enhanced Editor by setting Enhanced Editor options. To open the Enhanced Editor Options window, activate an Editor window and select Tools

Options

Enhanced Editor

Click the tabs that are located along the top of the window to navigate to the settings that you want to change, and then select the options that you want.

For example, Show line numbers specifies whether to display line numbers in the margin. When line numbers are displayed, the current line number is red. Insert spaces for tabs specifies whether to insert the space character or the tab character when you press the Tab key. If it is selected, the space character is used. If it is not selected, the tab character is used.

When you are finished, click OK.

You use the Program Editor window to submit SAS programs. You can also enter and edit SAS programs in this window, or you can open existing SAS programs that you created in another text editor.

To edit SAS programs in the Program Editor window, you can display line numbers. Then you can use text editor line commands and block text editor line commands within the line numbers to insert, delete, move, and copy lines within the Program Editor window.

In some operating environments, line numbers appear in the Program Editor window by default. In other systems, the use of line numbers is optional. Activating line numbers can make it easier for you to edit your program regardless of your operating environment.

To turn on line numbers, use the NUMS command. Type nums on the command line or in the command box and press Enter. To turn line numbers off, enter the NUMS command again. Line numbers activated using the NUMS command will remain in effect for the duration of your SAS session.

Text editor line commands enable you to delete, insert, move, copy, and repeat text. You enter these commands in the line number area in the Program Editor window.

The table below summarizes the basic text editing line commands.

You can use text editor line commands to perform actions like these:

In the example below, a PROC PRINT statement and a RUN statement need to be inserted after line 00004.

To insert the PROC PRINT and RUN statements in the program,

Block text editor line commands enable you to delete, repeat, copy, and move multiple lines in the Program Editor window.

The block text editor line commands include the following:

To use a block command, specify the command on the first line affected and on the final line affected, and then press Enter.

In the program below, the PROC TABULATE step needs to be deleted.

You can use the DD block command to remove the step. To use the DD command:

In the previous practice, SAS statements disappeared from the Program Editor window when you submitted them. However, you can recall a program to the Program Editor by selecting Run

The area in which submitted SAS code is stored is known as the recall buffer. Program statements accumulate in the recall buffer each time you submit a program. The recall buffer is last-in/first-out (the most recently submitted statements are recalled first).

For example, if you submit two programs, you will need to select Run

To save your SAS program to an external file, first activate the code editing window and select File

You can also save a SAS program by issuing a FILE command.

Suppose you want to save a program as D:ProgramsSasNewprog.Sas in the Windows operating environment. To do so, you can issue the following FILE command:

file 'd:programssas
ewprog.sas'

So far, the programs that you've submitted in this chapter have been error-free, but programming errors do occur. SAS can detect several types of errors. The most common are

This chapter focuses on identifying and correcting syntax errors.

When you submit a program, SAS scans each step for syntax errors, then processes the step (if no syntax errors are found). SAS then goes to the next step and repeats the process. Syntax errors, such as misspelled words, generally cause SAS to stop processing the step in which the error occurred.

You already know that information is written to the Log window while a SAS program is executing. When a program that contains an error is submitted, messages regarding the problem also appear in the Log window. When a syntax error is detected, the Log window

The program below contains a syntax error. The DATA step copies the SAS data set Clinic.Admit into a new data set named Clinic.Admitfee. The PROC step should print the values for the variables ID, Name, Actlevel, and Fee in the new data set. However, print is misspelled in the PROC PRINT statement.

data clinic.admitfee;
   set clinic.admit;
run;
proc prin data=clinic.admitfee;
   var id name actlevel fee;
run;

When the program is submitted, messages in the Log window indicate that the procedure PRIN was not found and that SAS stopped processing the PRINT step due to errors. No output is produced by the PRINT procedure, because the second step fails to execute.

After correcting your program, you can submit it again. However, before doing so, it's a good idea to clear the messages from the Log window so that you don't confuse the old error messages with the new messages. Then you can resubmit the program and view any resulting output.

Remember to check the Log window again to verify that your program ran correctly.

Each step in a SAS program is compiled and executed independently from every other step. As a step is compiled, SAS recognizes the end of the current step when it encounters

When the program below is submitted, the DATA step executes, but the PROC step does not. The PROC step does not execute because there is no following DATA or PROC step to indicate the beginning of a new step, nor is there a following RUN statement to indicate the end of the step.

data clinic.admitfee;
   set clinic.admit;
run;
proc print data=clinic.admitfee;
   var id name actlevel fee;

Because there is nothing to indicate the end of the PROC step, the PRINT procedure waits before executing, and a "PROC PRINT running" message appears at the top of the active window.

To correct the error, submit a RUN statement to complete the PROC step.

run;

If you are using the Program Editor window, you do not need to recall the program to the Program Editor window.

One of the most common errors is the omission of a semicolon at the end of a statement. The program below is missing a semicolon at the end of the PROC PRINT statement.

data clinic.admitfee;
  set clinic.admit;
run;
proc print data=clinic.admitfee
   var id name actlevel fee;
run;

When you omit a semicolon, SAS reads the statement that lacks the semicolon, plus the following statement, as one long statement. The SAS log then lists errors that relate to the combined statement, not the actual mistake (the missing semicolon).

To correct the error, do the following:

Some syntax errors, such as the missing quotation mark after HIGH in the program below, cause SAS to misinterpret the statements in your program.

data clinic.admitfee;
   set clinic.admit;
   where actlevel='HIGH;
run;
proc print data=clinic.admitfee;
   var id name actlevel fee;
run;

When the program is submitted, SAS is unable to resolve the DATA step, and a "DATA STEP running" message appears at the top of the active window.

When unbalanced quotation marks appear in a program that contains TITLE or FOOTNOTE statements, there is sometimes a warning in the SAS log which indicates that

When you have unbalanced quotation marks, SAS is often unable to detect the end of the statement in which it occurs. Simply adding a quotation mark and resubmitting your program usually does not solve the problem. SAS still considers the quotation marks to be unbalanced.

Therefore, you need to resolve the unbalanced quotation mark by canceling the submitted statements (in the Windows and UNIX operating environments) or by submitting a line of SAS code (in the z/OS operating environment) before you recall, correct, and resubmit the program.

To resolve the error in the Windows operating environment:

To resolve the error in the UNIX operating environment:

To resolve the error in the z/OS operating environment:

An invalid option error occurs when you specify an option that is not valid in a particular statement. In the program below, the KEYLABEL option is not valid when used with the PROC PRINT statement.

data clinic.admitfee;
   set clinic.admit;
run;
proc print data=clinic.admitfee keylabel;
   label actlevel='Activity Level';
run;

When a SAS statement that contains an invalid option is submitted, a message appears in the Log window indicating that the option is not valid or not recognized.

To correct the error:

You can insert comments into a SAS program to document the purpose of the program, to explain segments of the program, or to describe the steps in a complex program or calculation. A comment statement begins and ends with a comment symbol.

There are two forms of comment statements:

  *text;

or

   /*text*/

SAS ignores text between comment symbols during processing.

The following program shows some of the ways comments can be used to describe a SAS program.

 /* Read national sales data for vans */ 
 /* from an external raw data file */
data perm.vansales;
   infile vandata;
   input @1 Region $9.
          @13 Quarter 1. /* Values are 1, 2, 3, or 4 */
         @16 TotalSales comma11.;
  /* Print the entire data set */
proc print data=perm.vansales;
run;

SAS includes several system options that enable you to control error handling and Log window messages. The table shown below contains brief descriptions of some of these options. You can use either the OPTIONS statement or the SAS System Options window to specify these options.

If you are using the Enhanced Editor, you can use its color-coding for program elements, quoted strings, and comments to help you find coding errors.

You can also search for

See the following table for suggestions about finding syntax errors using the Enhanced Editor.

Debugging is the process of removing logic errors from a program. Unlike most syntax errors, logic errors do not stop a program from running. Instead, they cause the program to produce unexpected results.

You can debug logic errors in DATA steps by using the DATA step debugger. This tool allows you to issue commands to execute DATA step statements one by one, and then to pause to display the resulting variables' values in a window. By observing the results that are displayed, you can determine where the logic error lies.

The debugger can be used only in interactive mode. Because the debugger is interactive, you can repeat the process of issuing commands and observing results as many times as needed in a single debugging session. To invoke the debugger, add the DEBUG option to the DATA statement, and execute the program.

data perm.publish / debug;
   infile pubdata;
    input BookID $ Publisher & $22. Year;
run;
proc print data=perm.publish;
run;