"File types"

[Hans Franke]

On Tuesday 29 August 2006 01:01 pm, Chuck Guzis wrote:
> How many ways are there of representing variable length character strings?
> And how many have you run into? Off the top of my head,  I've seen--on the
> MS-DOS/Windows platform the following:   byte count+data, word count+data,
> data terminated by 00, data terminated by 0a,  data terminated by 0d, data
> terminated by 1F,  and probably a few others that don't occur to me right
> off.

Well, in general you have two ways:

a) Externaly - aka Length terminated
   Due some way you know how many symbols there are
b) Internaly - aka Stop marker
   A special Symbol or set of symbols marks the end

All can be seen as records/structures with the two components.

Classic subcategories are

a1) Length before the string (structure with two elements)
a2) Length in a different place (e.g. some list, or a structure
    with stringlength and pointer)

b1) A dedicated symbol after the last - e.g. x'00, '$', etc.
    that does not is part of the information
b2) A modifier, like using 2^8 as an endmarker - eg. the last
    symbol has this bit set (or not set) 

You may form endless variations of these concepts - as many
as you got time on your hand, and belive me, the last 50 years
gave developers quite some time to invent the world over and over.

Gruss
H.

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