TCL, read in specific line of input
Lim kiang Leng
such as: Do tcl have a build in command to perform the task below?
set spofile [open test.txt a+]
while { [gets $spofile line] >= 0 } {
incr line_no
if { $line_no == 4 } {
puts " i have read in line 4"
}
}
Bryan Oakley
That's the way to do it.
Asif
or
set line_no 4
set spofile [open test.txt a+]
for {set i 1} {$i <= $line_no} {incr i} { gets $spofile line ; }
Donal K. Fellows
> or
> set line_no 4
> set spofile [open test.txt a+]
> for {set i 1} {$i <= $line_no} {incr i} { gets $spofile line ; }
> puts "i have read in line 4"
That's not so good if you have a file with only three lines in it. :^)
Lim's solution is best for text files. You can do better than that if
you have files where every line is the same length, since then you can
use [seek] to go to exactly the right spot, but that doesn't work with
variable-length records (or not without a separate index file, which
makes everything quite a bit more complex.)
Donal.
Bryan Schofield
> According to Donal K. Fellows <donal.k...@man.ac.uk>:
> string at newlines, then pick up the appropriate list entry.
>
> But the bottom line is that many of the current operating systems do not
> provide a function to retrieve a specific line of a text file.
Just so everyone knows, this question was asked in couple of places so
to consolidate the different answers: