strip/4—remove specified characters from specified parts of a string
The strip/4 function removes specified characters from specified parts of a string. The general syntax for this function is as follows:
strip/4 arguments
Argument | Mode | Type | Description |
|---|---|---|---|
$STR | Input | STRING | Specifies the base string from which specified characters are to be removed |
$POS | Input | INTEGER | Specifies the part(s) of the string from which specified characters are to be removed |
$CHARS | Input | STRING | Specifies the characters to be removed |
$NEWSTR | Output | STRING | Resulting string after the specified characters have been removed |
Use the strip/4 function to make a copy of the string $STR in another string $NEWSTR with all characters from $CHARS stripped off from position $POS.
The value of $POS determines the part or parts of the base string where the blank spaces are to be removed. Only the three least significant bits are considered, as shown:
Possible values for the $POS argument
$POS value | Binary value | Impacted part of the string |
|---|---|---|
0 | 000 | None |
1 | 001 | End |
2 | 010 | Middle |
3 | 011 | Middle and end |
4 | 100 | Beginning |
5 | 101 | Beginning and end |
6 | 110 | Beginning and middle |
7 | 111 | Beginning, middle, and end (entire string) |
A character of the base string is considered to be located in the beginning of the string, if it and all characters preceding it, are in the character set $CHARS.
A character of the base string is considered to be located in the end of the string, if it and all characters following it, are in the character set $CHARS.
A character of the base string is considered to be located in the middle of the string, if it is in the character set $CHARS and if it is neither in the beginning nor in the end of the string.
For example, a string contains the following characters:
The first character in the string up to, but not including, a is considered to be the beginning of the string.
The part of the string starting from the space after the e through the last character in the string is considered to be the end of the string.
The part of the string from the a through the e is considered to be the middle of the string.
strip/4 example
The variable $MSG gets the contents of the msg slot of the event with all blank spaces, # and ! characters removed, except at the end of the string. Any trailing sequence of those three characters at the end of the slot value are retained.
If $E.msg has the value from this example, $MSG will get the value abcde #!#.