<StringScanner>.SkipOverString()

[aschone]

I am trying to parse a file using StringScanner. I have encountered a situation where I am having trouble determining if the string contains two delimiters in a row representing a field that has a null value. I have been using <StringScanner>.SkipOverString("*") to reliably skip past each field delimiter. However when the string contains "**" (Two delimiters in a row) the command <StringScanner>.SkipOverString("*") skips past both delimiters instead of just the first one.

Is this the way it is supposed to work; or is this a bug? Could someone with version 12 test this for me?

I have broken out the relevant section of code that is causing me issues. Hopefully someone can look at this and let me know their thoughts on it.

DIM vTextC as C
vTextC  = "11.76**XX*"

DIM ss as P
ss = stringScanner.create(vTextC)
	
DIM vClp04C as C					'Monetary Amount - Claim Payment Amount	
vClp04C = ss.ScanToString("*")		

DIM vStartOffsetN as N
vStartOffsetN = ss.Offset

DIM vNumN as N
vNumN = ss.SkipOverString("*")		'This line is skipping Two characters instead of the expected one character jump

DIM vStopOffSetN as N
vStopOffSetN = ss.Offset
	
DIM vClp05C as C					'Monetary Amount - Patient Responsibility Amount
vClp05C = ss.ScanToString("*")
ss.SkipOverString("*")

Ui_msg_box("test", "Clp04: " + vClp04C + crlf(2) + "Start Offset: " + vStartOffsetN + crlf() + "Stop Offset: " + vStopOffSetN + crlf() + "Chars Skipped: " + vNumN + crlf(2) + "Clp05: " + vClp05C )

[Tim Kiebert]

Re: &lt;StringScanner&gt;.SkipOverString()

I think this is one of those working as intended and not expected. If you put "****" in the text in your example and then start increasing the asterics to look for watch what happens. I think the scanner keeps going till the furthest possible match. so if you search on "*" then it will find "*" 4 times. If you search on "**" then it will find that 2 times. But if you search on "***" then it will find that once and there is no block of three next so it stops.

If after you scan to "*" and the data is always after after 1 asteric then you could use ss.skipover(1)

Note: I could not get ss.skipover() to return a true value as advertised. May be that should be reported.

[G Gabriel]

Re: &lt;StringScanner&gt;.SkipOverString()

It is working as advertised, but, you are confusing alpha and yourself.
Strangely enough, I have done the same test that Tim did but hesitated to respond as I do not have v12. But when I saw Tim's response, I realized, it is the same in my version as in v12 but my conclusion is different from Tim's.
As advertised:
ScanToString() is supposed to go to the first occurrence of the string, and it does as evident in your example.
The second part is the confusing part.
As advertised , SkipOverString() is supposed to skip over the text you specified. It does.
But,
In your example, when it skips over the first *, it comes to the second one. And, as there is no other characters (breaking point) between the first and the second one, it does double duty and skips over the second one.

To illustrate that, I used alpha's example, but instead of one "writer" I put two. In the first example, there is a space between the two. In the second one, I removed the space.
Watch what happens here:

dim scanner as P
dim txt as C
txt = <<%text%
#This is wonderful prose written
#by a technical writer writer of note.
#%text%
scanner = stringscanner.create(txt)
? scanner.SkipToString("writer")
= .T.

? scanner.SkipOverString("writer")
? scanner.GetToOffset()
= This is wonderful prose written
by a technical writer

? scanner.getremainder()
= writer of note.

Now, change that text where you remove the space between writer writer:

dim scanner as P
dim txt as C
txt = <<%text%
#This is wonderful prose written
#by a technical writerwriter of note.
#%text%
scanner = stringscanner.create(txt)
? scanner.SkipToString("writer")
= .T.

? scanner.SkipOverString("writer")
= 12

? scanner.GetToOffset()
= This is wonderful prose written
by a technical writerwriter

? scanner.getremainder()
= of note.

It skiped 12 characters , writerwriter and see where the offset went to? the end of the second writer not the first.
I think, this is how it is meant to work.
If you wish to find a two consecutive * in a string, there are other means to do that. String scanner seems an over kill here.

[G Gabriel]

Re: &lt;StringScanner&gt;.SkipOverString()

Tim:
I am not sure about skipover(1) ?
The function takes a character not a numeric argument.

Andrew:
Here is an easy way to find two consecutive identical characters:

txt="abc**def"
x1=at("*",txt,1)
?x1
= 4
x2=at("*",txt,2)
= 5
?if(x2-x1=1, "Consecutive", "Not consecutive")
= "Consecutive"

Of course, you could use regex and other functions as well.

[Tim Kiebert]

Re: &lt;StringScanner&gt;.SkipOverString()

Tim:
I am not sure about skipover(1) ?
The function takes a character not a numeric argument.

http://wiki.alphasoftware.com/String...kipOver+Method
Actually it does take numeric. One of only a few scanner functions that do. I have used it as such and the help does say it as well.

[G Gabriel]

Re: &lt;StringScanner&gt;.SkipOverString()

Disregard. I was thing of .SkipOverString()

[G Gabriel]

Re: &lt;StringScanner&gt;.SkipOverString()

Another way to find 2 consecutive *, or in your case, find a blank "field" is simply to use word(), e.g.

txt="a,b,c,,e,,,f"
dim flds as c=""
x=occurs(",",txt)-1
for i=1 to x
	if word(txt,i,",")=""
		flds=flds+"field "+i+" is blank"+crlf()
	end if
next i
msgbox(flds)

You could also initialize the text in an array and search for those blank fields.

[aschone]

Re: &lt;StringScanner&gt;.SkipOverString()

Thank you for looking into it. It maybe working as intended however I disagree on the intent. This is the first time I have used stringscanner. When I was reading the documentation I thought it was funny that <StringScanner>.SkipOverString() returned the number of characters skipped. I figured if I really needed to know that I could just measure the length of the string presented in the argument. However now I understand why they return the characters skipped count.

In the interest of "get it working" I ended up extracted to the segment terminator then used Word() to grab the individual elements.

StringScanner may be overkill for this project however based on my initial research it is supposed to be faster than other string manipulation methods. I am re-writing this routine in hopes of gaining speed. The major vendors are able to read, format, and generate a printable report in less than a second. My first attempt at this resulted in a lag of several seconds up. Sometimes it is enough I can get up to get a cup of coffee and be back before the report is ready to print.