Has anyone developed a string parsing object ?

woodsmith

I don’t want to have to reinvent the wheel if someone has already written code to parse text strings.· Specifically I need to find the location of one string inside another.· Example:

String to search: “this is a string”
String to search for: “is”
·
Desired·results: the string “is” starts at character 6 in the string “this is a string”
·
If anyone has built, worked on or is working on a similar piece of code I would like to see it.
·
I am not quite sure where to start.· I was thinking first convert the string into an array of characters, however, I am not sure how to do that.

Any help would be greatly appreciated!


Background:
I have two devices, device A sends an ASCII string to device B.· I am trying to put the prop in the middle to solve a buffering problem that device B has and to remove some of the unnecessary characters from the string.

Phil Pilgrim (PhiPi)

My strings.spin object (http://forums.parallax.com/showthread.php?p=587930) includes a find_next function that will do what you want. It carries some baggage, though, in that it relies on my heap manager object for allocating and deallocating strings dynamically.

-Phil

Tom Walker

FWIW,
Technically, "is" appears at index 3 in your sample string.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Truly Understand the Fundamentals and the Path will be so much easier...

Paul

You could use LOOKDOWN to find the sequence by assigning value to each character. I haven't done this in Spin but a similar program works in Pbasic:

(some "Spinish" pseudocode[noparse]:)[/noparse]

repeat n from 1 to string_length··········· ' finding string length left to the student... [noparse];)[/noparse]
· val1 := lookdown (mystring(n) :" ","i","s") ' note begining " " to skip the "is" in "this"
· val2 := lookdown (mystring(n+1):" ","i","s")
· val3 := lookdown (mystring(n+2):" ","i","s")

· if val1*100 + val2*10 + val3 == 123 'need to use magnitudes cuz " is" would = "s i" (index 4) and
····················································· ' "is " (index3) if you just added val's. All would = 3
··· do_stringfound(n+1) ' use n+1 to skip the space

Post Edited (Paul) : 3/15/2007 6:40:05 PM GMT

Dennis Ferron

Tom Walker said...
FWIW,
Technically, "is" appears at index 3 in your sample string.

Actually it's index 2. The first index is 0.

Sorry I couldn't resist.

Tom Walker

Dennis,
That's what I said....hey...where did that 3 come from??!!! ;^)

...I could have said it depends on the language...I've worked in various "business BASICs" that allow you to decide whether indexes start at 0 or 1...but I just goofed...sleepy after lunch, I guess...

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Truly Understand the Fundamentals and the Path will be so much easier...