SPSS® 12.0 Command Syntax Reference

Options
LOOP—END LOOP 831
Missing Values. You can prevent cases with missing values for any of the variables used in
the loop structure from entering the loop (see “Missing Values” on p. 837).
Creating Data. A loop structure within an input program can be used to generate data (see
“Creating Data” on p. 838).
Defining Complex File Structures. A loop structure within an input program can be used to define
complex files that cannot be handled by standard file definition facilities (see pp. 509,
510, and 512 for examples).
Basic Specification
The basic specification is LOOP followed by at least one transformation command. The structure
must end with the END LOOP command. Commands within the loop are executed until
the cutoff is reached.
Syntax Rules
• If LOOP and END LOOP are specified before a working data file exists, they must be specified
within an input program.
• If both an indexing and an IF clause are used on LOOP, the indexing clause must be first.
• Loop structures can be nested within other loop structures or within DO IF structures, and
vice versa.
Operations
Example
• The LOOP command defines the beginning of a loop structure and the END LOOP command
defines its end. The END LOOP command returns control to LOOP unless the cutoff
has been reached. When the cutoff has been reached, control passes to the command immediately
following END LOOP.
• When specified within a loop structure, definition commands (such as MISSING VALUES
and VARIABLE LABELS) and utility commands (such as SET and SHOW) are invoked only
once, when they are encountered for the first time within the loop.
SET MXLOOPS=10.
LOOP. /*Loop with no limit other than MXLOOPS
COMPUTE X=X+1.
END LOOP.
• This and the following examples assume that a working data file and all of the variables
mentioned in the loop exist.