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How do I insert, (not overwrite) into a string?

( #29236=categorized question: print w/ replies, xml ) Need Help??
Contributed by Anonymous Monk on Aug 23, 2000 at 19:59 UTC
Q&A  > strings


Description:

eg, insert "H" at the begining of a string, without loosing the 0th element "ello" -> "Hello"

Answer: How do I insert, (not overwrite) into a string?
contributed by KM

Another way to do it:

my $str = "ello"; substr($str,0,0,"H");

Cheers,
KM

Answer: How do I insert, (not overwrite) into a string?
contributed by Shendal

my($str) = 'ello'; $str = "H$str";
Answer: How do I insert, (not overwrite) into a string?
contributed by KM

Did a quick benchmark out of curiosity:

KM:     substr($_,0,0,"H")
Ovid:    s/^(.*)$/H$1/
Shendal:  $_ .= "H".$_
turnstep: s/^/H/

Benchmark: timing 100000 iterations of KM, Ovid, Shendal, turnstep... KM: -1 wallclock secs ( 0.55 usr + 0.00 sys = 0.55 CPU) Ovid: 2 wallclock secs ( 2.20 usr + 0.00 sys = 2.20 CPU) Shendal: 0 wallclock secs ( 0.53 usr + 0.00 sys = 0.53 CPU) turnstep: 1 wallclock secs ( 0.98 usr + 0.00 sys = 0.98 CPU)

Cheers,
KM

Answer: How do I insert, (not overwrite) into a string?
contributed by turnstep

Regular expressions can handle this just fine as well:

my $string = "ello"; $string =~ s/^/Henry said H/;
Answer: How do I insert, (not overwrite) into a string?
contributed by davorg

my $str = 'ello'; my $char = 'H'; print $str, "\n"; substr($str, 0, 0, $char); print $str, "\n";
Answer: How do I insert, (not overwrite) into a string?
contributed by Ovid

There are several methods to do this. Shendal has listed one. Here are a couple of others:

# Concatenation my $str = 'ello'; $str = 'H' . $str; # Regex my $str = 'ello'; $str =~ s/^(.*)$/H$1/;
Cheers,
Ovid
Answer: How do I insert, (not overwrite) into a string?
contributed by redcloud

Just to follow-up KM and davorg, note that you can use substr() as an lvalue. It's just syntactic sugar, but I like the taste of it. 8^)

use strict; my $str = "ello"; substr($str,0,0) = "H"; print $str, "\n";
Answer: How do I insert, (not overwrite) into a string?
contributed by mphilip1

try this sub I wrote:

# sub signature: # insertXintoYatZ( X , Y , Z ) ; sub insertXintoYatZ{ my ( $X , $Y , $Z ) = @_; substr( $Y , $Z , -length($Y) ) = $X ; return $Y; } $s = "The black cat climbed the green tree"; print "s = $s \n"; print 'insert = '.($s = insertXintoYatZ( "tall ", $s , 26 ))."\n"; print " (now, s = '$s' ) \n"; # OUTPUT: # s = The black cat climbed the green tree # insert = 'tall ' # (now, s = 'The black cat climbed the tall green tree' )";
Answer: How do I insert, (not overwrite) into a string?
contributed by Fian

I know this is kinda long winded but if u wanna insert into a string split the thing into its constituent characters and bung em in an array then u can insert whatever u want wherever u want.....

@bitsOfString = split(//,$yourString);

Slán

Fian. Edited by davido: Added code tags.

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