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Rationale for 509 minimum character limit

I've seen a lot of the minimal requirements that an ANSI C compiler must support like 31 arguments to a function, and most of the numbers seem to make some kind of sense.

However, I cannot see the reasoning for supporting at least 509 characters in a source line. 511 or 512 would make more sense, but 509 seems kind of arbitrary.

What is the reason for this number?

Solution

  • This perhaps is to take account of possible CR + LF + '\0' characters and have a string representation of each line still fit into 512 bytes of memory.