5.2.5 Finding and removing leading/trailing whitespace
The trim command can find and/or remove
leading and trailing whitespace in a string
(see Section 21.2.2, Section 28.1.9
and Section 28.2.2 for other usages of trim).
-
trim takes one mandatory arguments and one or two optional arguments:
-
str, a string.
- Optionally, left or right, the symbol specifying an
one-sided truncation.
- Optionally, index, the symbol.
- trim(str ⟨,left|right ⟩
⟨,index ⟩) finds the index l of the first
non-whitespace character in str and the index u of the first trailing
whitespace character in str. If index is given, then the
return value is either l if left is given, u if right
is given, or (l,u−l) otherwise (the last sequence contains the start and length
of the truncated string). If index is omitted, then the return value is
the portion between the lth character (inclusive) and uth character
(exclusive); if left is given, then u=length(str),
and if right is given, then l=0.
- Whitespace characters in ASCII are: 9 (horizontal tab), 10 (line feed),
11 (vertical tab), 12 (form feed), 13 (carriage return) and 32 (space).
Instead of trim, you can also use the strip
command to remove whitespace, but note that it discards only space characters.
Examples
trim(" this is a string\n\t ") |
trim(" this is a string\n\t ",right) |