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

character data. Data errors do not cause a program to stop. Instead, they generate notes

in the SAS log. These are some of the types of data errors:

• defining a variable as numeric when the data value is actually character

• generating missing values as a result of performing an operation on missing values

• reading a variable with an INPUT statement when the variable is not in the correct

position in a file

• using the Sum statement with character variables

Semantic Errors

Semantic errors are another type of an execution-time error. They occur when the form

of a SAS statement is correct, but some elements are not valid in a particular usage.

These are some of the types of semantic errors:

• specifying the wrong number of arguments for a function

• using a numeric variable name where only character variables are valid

• using invalid references to an array

• using a libref that has not yet been assigned

Diagnosing Errors

Examples in This Section

Many of the programs in this section use university test scores to illustrate errors in the

SAS log. Other programs in this section use other data.

Diagnosing Syntax Errors

When SAS Detects a Syntax Error

The SAS Supervisor detects syntax errors as it compiles each step, and then SAS does

the following:

• writes the word ERROR to the log

• identifies the error's location

• writes an explanation of the error

Example: Missing Semicolon and Misspelled Keyword

In the following program, the CHART procedure is used to analyze data. Note that a

semicolon in the DATA statement is omitted, and the keyword INFILE is misspelled.

libname out 'your-data-library';

data out.error1

infill 'your-input-file';

input test $ gender $ year TestScore;

402 Chapter 25 • Diagnosing and Avoiding Errors

run;

proc chart data=out.error1;

hbar test / sumvar=TestScore type=mean group=gender discrete;

run;

The following output shows the result of the two syntax errors:

Log 25.1 Diagnosing Syntax Errors: Missing Semicolon and Misspelled Keyword

11 libname out 'your-data-library';

NOTE: Libref OUT was successfully assigned as follows:

Engine: V9

Physical Name: your-data-library

12

13 data out.error1

14 infill 'your-input-file';

15 input test $ gender $ year TestScore;

16 run;

ERROR: No DATALINES or INFILE statement.

ERROR: Extension for physical file name "your-input-file" does not

correspond to a valid member type.

NOTE: The SAS System stopped processing this step because of errors.

WARNING: The data set OUT.ERROR1 may be incomplete. When this step was stopped

there were 0

observations and 4 variables.

WARNING: Data set OUT.ERROR1 was not replaced because this step was stopped.

WARNING: The data set WORK.INFILL may be incomplete. When this step was stopped

there were 0

observations and 4 variables.

WARNING: Data set WORK.INFILL was not replaced because this step was stopped.

NOTE: DATA statement used (Total process time):

real time 0.00 seconds

cpu time 0.00 seconds

17

18 proc chart data=out.error1;

19 hbar test / sumvar=TestScore type=mean group=gender discrete;

20 run;

NOTE: No observations in data set OUT.ERROR1.

NOTE: PROCEDURE CHART used (Total process time):

real time 0.00 seconds

cpu time 0.00 seconds

As the log indicates, SAS recognizes the keyword DATA and attempts to process the

DATA step. Because the DATA statement must end with a semicolon, SAS assumes that

INFILL is a data set name, and that two data sets are being created: OUT.ERROR1 and

WORK.INFILL. Because SAS considers INFILL the name of a data set, it does not

recognize it as part of another statement, and therefore does not detect the spelling error.

Because the string in quotation marks is invalid in a DATA statement, SAS stops

processing here and created no observations for either data set.

SAS attempts to execute the program logically based on the statements that it contains,

according to the steps outlined earlier in this section. The second syntax error, the

misspelled keyword, is never recognized because SAS considers the DATA statement to

be in effect until a semicolon ends the statement. The point to remember is that when

multiple errors are made in the same program, not all of them might be detected the first

time the program is executed. Errors might also be flagged differently in a group than if

Diagnosing Errors 403