Core Function InStrRev

InStrRev( <string>, <substirng>, <casesense>, <occurrence>, <start>, <length> )

Description

Same as InStr() but searches from right to left instead of left to right.

Parameters

string

The string to evaluate.

substring

The substring to search for.

ignoreCase

Optional; Flag to indicate if the operations should be case insensitive.

true = not case sensitive

false = case sensitive

Default: true

occurrence

Optional; Which occurrence of the substring to find in the string. Use a negative occurrence to search from the right side.

The default value is 1 (finds first occurrence).

start

Optional; The starting position of the search.

OR

If the start is a negative value the character position will work backwards from the length of the string.

Default: 0

length

Optional; The number of characters to search. By default the entire remainder of the string.

If length is given and is negative, then that many characters will be omitted from the end of string (after the start position has been calculated when a start is negative). If start denotes the position of this truncation or beyond, -1 will be returned.

Return Value

Success: Returns the position of the substring.

Failure: Returns -1.

Remarks

The first character position is 0.

You might think you set the start to say 10 (in a string of size 20) then expect InStrRev() to search backwards from that point but you will be mistaken as InStrRev() will search from the END of the string to the start you mentioned (10). To solve this issue you should set the start to 0 and the length to 10 then it will correctly search from position 10 to the start (0).

This is because InStrRev() works similar to InStr() and SubStr() in how it handles start/length in that the start+length defines WHAT will be searched (the entire search content is defined in the start+length).

Example

$TestString = "the quick brown fox jumps over the lazy dog";
 
$TestNumber = InStrRev($TestString, "the"); // 31
say $TestNumber . " | " . substr($TestString, $TestNumber, 3);
 
$TestNumber = InStrRev($TestString, "the", true, 1, 0, 16); // 0
say $TestNumber . " | " . substr($TestString, $TestNumber, 3);
 
// PRINTS
// 31 | the
// 0 | the