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How do I delete the first n characters on a line

by CyCliC (Novice)
on Jul 18, 2001 at 11:51 UTC ( #97571=categorized question: print w/replies, xml ) Need Help??
Contributed by CyCliC on Jul 18, 2001 at 11:51 UTC
Q&A  > files

Answer: how do i delete the first n characters on a line
contributed by jmcnamara

Use substr:

# substr EXPR,OFFSET,LENGTH,REPLACEMENT my $n = 3; my $str1 = "1234567890\n"; my $str2 = substr($str1, $n); print $str1; # 1234567890 print $str2; # 4567890


Answer: How do I delete the first n characters on a line
contributed by ar0n

substr($str, 0, $n) = "";

Answer: How do I delete the first n characters on a line
contributed by tachyon

You could also use a regex although this is not as fast as substr.

my $n = 3; my $str = "1234567890\n"; $str =~ s/^.{$n}//s; # was: $str =~ s/^.{$n}(.*)$/$1/s; print $str;

The difference with the regex solution is that if $n > length $str no change will be made. With substr you will get a null string left in $str if you try to delete more chars than exist in $str. You need the /s modifier to make the . match a newline which is a valid char.



To get the same behavior as a substr solution use: $str =~ s/^.{1,$n}//s;

Edit by tye to incorporate I0's reply

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