indexof_regex()

Learn how to use the indexof_regex() function to return the zero-based index position of a regex input.

Returns the zero-based index of the first occurrence of a specified lookup regular expression within the input string.

See indexof().

Syntax

indexof_regex(string,match[,start[,length[,occurrence]]])

Parameters

NameTypeRequiredDescription
stringstring✔️The source string to search.
matchstring✔️The regular expression lookup string.
startintThe search start position. A negative value will offset the starting search position from the end of the string by this many steps: abs(start).
lengthintThe number of character positions to examine. A value of -1 means unlimited length.
occurrenceintThe number of the occurrence. The default is 1.

Returns

The zero-based index position of match.

  • Returns -1 if match isn’t found in string.
  • Returns null if:
    • start is less than 0.
    • occurrence is less than 0.
    • length is less than -1.

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's no second occurrence in the search range
    idx4 = indexof_regex("ababaa", @"a.a", 0, -1, 2), // Matches don't overlap so full lookup can't be found 
    idx5 = indexof_regex("abcabc", @"a|ab", -1)  // invalid start argument

Output

idx1idx2idx3idx4idx5
03-1-1