= SPSS Macro String Functions =

SPSS macros offer the following library of '''string functions'''.

<<TableOfContents>>

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== Quoting ==

Quoting is technically optional within a macro, as all values within a macro are technically strings. Nonetheless, it is best practice to quote strings properly.

Consider the following:

||'''Expression'''                   ||'''Result''' ||
||`!UPCASE(abc)`                     ||`ABC`        ||
||`!UPCASE('abc')`                   ||`ABC`        ||
||`!UPCASE(a b c)`                   ||error        ||
||`!UPCASE('a b c')`                 ||`A B C`      ||
||`!UPCASE(a/b/c)`                   ||error        ||
||`!UPCASE('a/b/c')`                 ||`A/B/C`      ||
||`!UPCASE(!CONCAT(a,b,c))`          ||`ABC`        ||
||`!UPCASE(!CONCAT('a','b','c'))`    ||`ABC`        ||
||`!UPCASE(!CONCAT(a, b, c))`        ||`ABC`        ||
||`!UPCASE(!CONCAT('a ','b ','c '))` ||`A B C`      ||
||`!UPCASE(!CONCAT('a,b,c'))`        ||`A,B,C`      ||
||`!QUOTE(abc)`                      ||`'ABC'`      ||
||`!QUOTE('abc')`                    ||`abc`        ||
||`!QUOTE('Bill"s')`                 ||`'Bill"s'`   ||
||`!QUOTE("Bill's")`                 ||`"Bill's"`   ||
||`!QUOTE(Bill's)`                   ||error        ||
||`!QUOTE(!UNQUOTE('Bill"s'))`       ||`'Bill"s'`   ||

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== Functions ==

'''`!blanks(N)`''' returns a string composed of N blank spaces.

'''`!concat(value...)`''' concatenates all values.

'''`!eval(value)`''' scans a value for macros and evaluates. This is necessary for evaluating an externally defined macro within a macro definition.

'''`!head(value...)`''' copies the first token from the values.

'''`!index(value, pattern)`''' returns the integer position of a `pattern` inside a `value`. If the `value` does not contain the `pattern`, this function returns 0.

'''`!length(value)`''' returns the integer length of a value.

'''`!null`''' returns an empty string. This is mostly useful for checking if a macro parameter was specified (i.e. `!IF (!1 !NE !NULL)`).

'''`!quote(value)`''' returns the value quoted, with internal quotes escaped.

'''`!substr(value, index [, length])`''' copies a substring from a value. The substring starts at position `index` and continues for `length` characters. If `length` is not specified, the substring copies until the end of the original value.

'''`!tail(value...)`''' copies the second through last tokens from the values. The complement to `!head()`.

'''`!unquote(value)`''' returns the value un-quoted, with internal escaped quotes un-escaped.

'''`!upcase(value)`''' translates lowercase characters into uppercase.



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