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Problem printing in colors

by hotshot (Prior)
on Apr 28, 2005 at 16:09 UTC ( [id://452373]=perlquestion: print w/replies, xml ) Need Help??

hotshot has asked for the wisdom of the Perl Monks concerning the following question:

Hi all,

I'm trying to use colors in my application (perl 5.8.0 on Linux) and have some difficulties combining it with printf(). Example:
# when I perform:
printf "\n\t%-25s| %-25s\n", 'Filename', 'Comment';

# I get on STDOUT
Filename                 Comment              # please note the spacin
+g

# when I perform
printf "\n\t%-25s| %-25s\n", RED . 'Filename' . RESET, UNDERLINE . 'Co
+mment' . RESET;   # the same spacing as above

# I get on STDOUT
Filename          Comment           # each underlined, but the spacing
+ is changed somehow

[download]
Why adding the underline constant messes with my spacing?



Hotshot

Replies are listed 'Best First'.
Re: Problem printing in colors
by salva (Canon) on Apr 28, 2005 at 16:15 UTC
    because perl knows nothing about ANSI escape sequences, it just see them as normal characters and count them inside %-25s formats.

    Insert them with additional formaters, i.e: 

    printf "\n\t%s%-25s%s| %s%-25s%s\n", RED, 'Filename', RESET, UNDERLINE
+, 'Comment', RESET;

    [download]
[reply]
[d/l]
Re: Problem printing in colors
by blazar (Canon) on Apr 28, 2005 at 16:35 UTC
    Why adding the underline constant messes with my spacing?
    Because the "underline constant" is an ANSI sequence, which in turn is nothing but a string and perl -or better: sprintf()- takes its lenght into account, but then its length "disappears" when it is interpreted by the terminal.
[reply]
[d/l]

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