SPSS® 12.0 Command Syntax Reference

48 Universals
Conversion Functions
of the substrings. With the same value X**X**X* for ALPHA8,
RINDEX (ALPHA8, ’**X*’, 2) returns 7, and RINDEX (ALPHA8, ’**X*’, 1)
returns 8. a3 must be a positive integer and must divide evenly into the
length of a2. The target variable must be numeric. If a2 is not found
within a1, the value 0 is returned.
NUMBER(arg,format) Convert the argument into a number using the specified format. The
argument is string, the format is a numeric format, and the result is
numeric. The string is essentially reread using the format and returned
as a number. For example, NUMBER (XALPHA,F3.1) converts all values
for XALPHA to numbers using the F3.1 format. The function returns the
system-missing value if the conversion is invalid.
STRING(arg,format) Converts the argument into a string using the specified format. The
argument is numeric, the format is a numeric format, and the result is a
string. The number is converted from internal representation according
to the format and then stored as a string. For example, STRING (INCOME,
DOLLAR8) converts the numeric values for INCOME to the dollar format
and returns it as a string value. If the result is shorter than the string
variable that receives the values, it is right-justified. If the result is
longer, it is right-trimmed.
Missing Values in String Expressions
• If the numeric argument (which can be an expression) for functions LPAD and RPAD is
illegal or missing, the result is a null string. If the padding or trimming is the only
operation, the string is then padded to its entire length with blanks. If the operation is
nested, the null string is passed to the next nested level.
• If a numeric argument to SUBSTR is illegal or missing, the result is a null string. If SUBSTR
is the only operation, the string is blank. If the operation is nested, the null string is passed
to the next nested level.
• If a numeric argument to INDEX or RINDEX is illegal or missing, the result is system-missing.
Logical Expressions
Logical expressions can appear on the IF, SELECT IF, DO IF, ELSE IF, LOOP IF, and END
LOOP IF commands. SPSS evaluates a logical expression as true or false, or as missing if
it is indeterminate. A logical expression returns 1 if the expression is true, 0 if it is false,
or system-missing if it is missing. Thus, logical expressions can be any expressions that
yield this three-value logic.
• The simplest logical expression is a logical variable. A logical variable is any numeric
variable that has values 1, 0, or system-missing. Logical variables cannot be strings.