FA-95907 / Postal address normalization / Member archive

Five-or-nine digit postal code: placeholder plus-four is kept · case 02

"12029-0000" is returned with its placeholder extension instead of "12029".

Member previewVariant 2 · 3 implementations · 12 checks per implementation

Case contract

Input a string or an integer. Integers are zero-padded to 5 digits when <= 99999, else to 9. Strings are stripped; a 10-character string with "-" or a space at index 5 loses that separator. Valid results are exactly 5 or 9 ASCII digits; 9 digits render "DDDDD-DDDD" unless the last four are "0000", which renders the 5-digit form. Anything else returns None.

Why this case matters

Postal codes arrive from spreadsheets, forms and legacy files; losing leading zeros or accepting malformed codes misroutes mail and breaks deduplication.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
zero plus-four is dropped	`"23049-0000"`	`"23049"`	Failed

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