C Parse Questino

DaFrEQ · 05-05-2003, 01:52 PM

Hey all,

Let's say I've got a file that has data in it. The data is written 1 line at a time. 1 line of data holds about 30 chars or so.

What would be the best way to (within a proggie) parse a data text file, say test.dat which has about 20 lines of 30 characters.

The data is written to each line with numerical values, spaces as separators, and the EOL is simply a ^M or NULL string.

Any ideas of where I can grab a sample bit of code to start me off?

Tnx.

L8rz

Tinkster · 05-05-2003, 05:55 PM

That would, I guess, depend on the post-processing :)

Do you intend to handle the numbers individually?

Cheers,
Tink

yrraja · 05-06-2003, 02:12 AM

Like Tink said it would depend on the post-processing. The steps that would be involved may be:

1) Open a file
2) Read a line using 'fgets'
3) Use 'sscanf' to read in the 30 numeric values in 30 different variables.
4) Do the required processing on these variables
5) If not EOF then go back to step 2

Yaser

DaFrEQ · 05-06-2003, 08:03 AM

Well, the post processing hasn't been determined yet. I'm just trying to find out the best way to parse line by line just to extract the data from said text data file, and feed the data into something else... say a viewport on screen... or even print it to the console as it scrolls in.

solspin · 05-06-2003, 12:57 PM

Try this link out:
http://computer.howstuffworks.com/c8.htm

yrraja · 05-06-2003, 11:18 PM

if the line data is in a fixed format like you said earlier that 30 numeric values then 'fgets' and 'sscanf' can do the trick for you.

If the number of values is not fixed then it will need some extra processing.

DaFrEQ · 05-07-2003, 08:43 AM

Thanks. I was just trying to figure out between fgets, scanf, and just soaking up the entire string into an array to be parsed however. (given the fixed format)
I guess I could put a simple loop in to check for the '\n' and EOF so I can parse it all at once and throw it to the correct place in code.

L8rz

yrraja · 05-07-2003, 11:00 PM

Do look into strtok() and strstr() functions. For variable number of numeric values you can first read a line with fgets() and then one by one read a numeric value using strtok(). The you can use sscanf() to read that value as an interger.

Yaser

BoldKiller · 05-15-2003, 09:04 PM

Looks like your doing this in C. Have you taught about :

cin >>

DaFrEQ · 05-16-2003, 08:15 AM

already took care of it.
tnx

L8rz

powerplane · 05-16-2003, 09:06 PM

My suggestion is to use lex/flex, or some regular expression lib. It may not run as quickly as a man-code parser, but the code will be very easy to read and change.