The original string.
The characters to replace.
The characters to replace with.
String containing modifiers.
Modifiers:
| Modifier | Description |
| 'c' | Complement the list of characters in from |
| 'd' | Removes matching characters with no corresponding replacement in to |
| 's' | Removes adjacent duplicates in the replaced characters |
If the modifier 'd' is present, then the number of characters in to may be only 0 or 1.
If the modifier 'd' is not present, and to is empty, then to is taken to be the same as from.
If the modifier 'd' is not present, and to is shorter than from, then to is extended by replicating the last character in to.
Both from and to may contain ranges using the '-' character (e.g. "a-d" is synonymous with "abcd".) Neither accept a leading '^' as meaning the complement of the string (use the 'c' modifier for that).
assert(tr("abcdef", "cd", "CD") == "abCDef"); assert(tr("1st March, 2018", "March", "MAR", "s") == "1st MAR, 2018"); assert(tr("abcdef", "ef", "", "d") == "abcd"); assert(tr("14-Jul-87", "a-zA-Z", " ", "cs") == " Jul ");
Replaces the characters in str which are in from with the the corresponding characters in to and returns the resulting string.
tr is based on Posix's tr, though it doesn't do everything that the Posix utility does.