Learning Perl, Second Edition

11.4. More About the Fieldholders

So far, by example, you know that the fieldholder @<<<< means a five-character left-justified field and that @<<<<<<<<<< means an 11-character left-justified field. Here's the whole scoop, as promised earlier.

11.4.1. Text Fields

Most fieldholders start with @. The characters following the @ indicate the type of field, while the number of characters (including the @) indicates the field width.

If the characters following the @ are left-angle brackets (<<<<), you get a left-justified field; that is, the value will be padded on the right with spaces if the value is shorter than the field width. (If a value is too long, it's truncated automatically; the layout of the format is always preserved.)

If the characters following the @ are right-angle brackets (>>>>), you get a right-justified field—that is, if the value is too short, it gets padded on the left with spaces.

Finally, if the characters following the @ are vertical bars (||||), you get a centered field: if the value is too short, it gets padded on both sides with spaces, enough on each side to make the value mostly centered within the field.

11.4.2. Numeric Fields

Another kind of fieldholder is a fixed-precision numeric field, useful for those big financial reports. This field also begins with @, and is followed by one or more #'s with an optional dot (indicating a decimal point). Once again, the @ counts as one of the characters of the field. For example:

format MONEY = Assets: @#####.## ...