What does Intel IPP status -185 (ippStsRegExpBackRefErr) mean?

 
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ippStsRegExpGroupingErr ippStsRegExpChClassErr

ippStsRegExpBackRefErr

This compile-time status is raised when a back reference cannot be resolved to a valid capturing group in the pattern accepted by IPP.

Named groups, noncapturing groups, branch-local numbering, and escaped digits are common sources of confusion when a pattern is moved between regex engines. Verify the capture numbering as IPP sees it, not as another engine reports it.

Useful checks

  • Count only capturing groups, not noncapturing groups.
  • Check whether a digit was meant literally and should be escaped differently.
  • Confirm that the referenced group exists before the back reference according to the supported syntax.

Intel IPP RegExp functions · Perl regular expression reference


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