indexof_regex()
Returns the zero-based index of the first occurrence of a specified lookup regular expression within the input string.
See indexof().
Syntax
indexof_regex(source,lookup[,start_index[,length[,occurrence]]])
Arguments
| Arguments | Description | Required or Optional |
|---|---|---|
| source | Input string | Required |
| lookup | Regular expression lookup string. | Required |
| start_index | Search start position | Optional |
| length | Number of character positions to examine. -1 defines an unlimited length | Optional |
| occurrence | Find the index of the N-th appearance of the pattern. | |
| Default is 1, the index of the first occurrence | Optional |
Returns
Zero-based index position of lookup.
- Returns -1 if the string isn't found in the input.
- Returns null if:
- start_index is less than 0.
- occurrence is less than 0.
- length parameter is less than -1.
Note
- Overlapping matches lookup aren't supported.
- Regular expression strings may contain characters that require either escaping or using @'' string-literals.
Examples
print
idx1 = indexof_regex("abcabc", @"a.c") // lookup found in input string
, idx2 = indexof_regex("abcabcdefg", @"a.c", 0, 9, 2) // lookup found in input string
, idx3 = indexof_regex("abcabc", @"a.c", 1, -1, 2) // there is no second occurrence in the search range
, idx4 = indexof_regex("ababaa", @"a.a", 0, -1, 2) // Matches do not overlap so full lookup can't be found
, idx5 = indexof_regex("abcabc", @"a|ab", -1) // invalid start_index argument
| idx1 | idx2 | idx3 | idx4 | idx5 |
|---|---|---|---|---|
| 0 | 3 | -1 | -1 |