Code128C Generator — digits, packed in pairs

Code128C is the numeric code set of Code 128. Instead of encoding one digit per module pair like Set B, a Code128C symbol maps every two-digit group — 00 through 99 — to a single module pair. A 20-digit number therefore takes only 10 encoding positions, making the Code128C barcode dramatically narrower.

Because each module pair must carry exactly two digits, a valid Set C value is an even-length string of digits and nothing else. That constraint is real, not bureaucratic: scanners decode pairs, so an odd trailing digit has no slot to live in inside the symbol.

This generator enforces those rules strictly. Enter 12345678 and you get a true Set C symbol starting with the Start-C pattern. Enter 1234567 and you get a clear error — the tool never pads a zero, drops a digit, or quietly falls back to Set B.

Code 128 patterns encode values 0–105 per module pair. Set B spends one pair per character, so the digits “42” cost two pairs. A Code128C symbol assigns the value 42 to a single pair, encoding both digits at once. For a 30-digit serial number that is the difference between 30 encoding positions and 15 — roughly half the printed width at the same bar size, which is exactly why long numeric runs prefer Code128C.

Compactness matters on small labels, curved surfaces and dense packing sheets, where a narrower symbol leaves room for bigger bars (easier scanning) or more labels per sheet. At equal physical width, Set C simply carries more digits than its Set B equivalent.

Code128C appears wherever systems count in long digit runs: serialized inventory tags, container and pallet markings, courier parcel numbers, and production counters. These systems usually generate even-width numbers by design, which fits Code128C naturally.

If your numbering scheme produces odd widths — say a 7-digit item code — decide deliberately: either widen the scheme (add a leading zero at the source) or use Code 128B. Never let a tool guess for you; this Code128C generator won’t.

Every value passes two gates before rendering: a character gate (digits only) and a parity gate (even count). Each symbol also carries a mod-103 check character computed from the encoded pairs, so scanners verify the pattern itself on every scan. The result is a barcode where both the input rules and the printed output are machine-checked.