|REBOL 3 Docs||Guide||Concepts||Functions||Datatypes||Errors|
|TOC < Back Next >||Updated: 6-Feb-2009 Edit History|
Text files can be easily accessed and managed as individual lines of text, rather than as a single series of characters. For example, to read a file as a block of lines:
lines: read/lines %service.txt
The above example returns a block containing a series of strings (one for each line) without line terminators. Empty lines are represented by empty strings.
To print a specific line you use the following code:
print first lines print last lines print pick lines 100 print lines/500
To print all of the lines of a file, use the following line of code:
foreach line lines [print line] I wanted the gold, and I sought it, I scrabbled and mucked like a slave. Was it famine or scurvy -- I fought it; I hurled my youth into a grave. I wanted the gold, and I got it -- Came out with a fortune last fall, -- Yet somehow life's not what I thought it, And somehow the gold isn't all.
To print all of the lines that contain the string gold, use the following line of code:
foreach line lines [ if find line "gold" [print line] ] I wanted the gold, and I sought it, I wanted the gold, and I got it -- And somehow the gold isn't all.
You can write the text file out as lines using the write function:
write/lines %output.txt lines
To write out specific lines from a block, use:
write/lines %output.txt [ "line one" "line two" "line three" ]
In fact, the functions read/lines and write/lines can be combined to process files one line at a time. For example the following code removes all of the comments from a REBOL script:
script: read/lines %script.r foreach line script [ where: find line ";" if where [clear where] ] write/lines %script1.r script
Files can be read as lines from a network as well:
data: read/lines http://www.rebol.com print pick (read/lines ftp://ftp.rebol.com/test.txt) 3 new
In addition /lines can be used with /append to append lines from a block to a file.
|TOC < Back Next >||REBOL.com - WIP Wiki||Feedback Admin|