How do I count blocks of characters in a string variable?

[Researcher]

I'm trying to create a code to count a certain character in a string,
lets say that I want to know how many letters "o" there are in the
text "The book is yellow", I'd use the following code:

$text = "The book is yellow";
@characters = split (//,$text);
foreach $char (@characters){
if ($char eq "o"){
$count++;
}
}

Very easy, but I think this is a lot of code for such a simple task,
there's got to be a simpler way to do this, besides, what if I want to
count a block of characters instead of one only (e.g. how many "el"
there are in $text)? How do I do this?

I hope someone can help me with this.

[Jeff 'japhy' Pinyan]

On 6 Sep 2003, Researcher wrote:

>I'm trying to create a code to count a certain character in a string,
>lets say that I want to know how many letters "o" there are in the
>text "The book is yellow", I'd use the following code:
>
>$text = "The book is yellow";
>@characters = split (//,$text);
>foreach $char (@characters){
> if ($char eq "o"){
> $count++;
> }
>}

If you just want to count the number of times a character occurs in a
string, use the tr/// operator.

$o_count = $string =~ tr/o//;

Read 'perldoc perlop' for more on tr///.

--
Jeff Pinyan RPI Acacia Brother #734 2003 Rush Chairman
"And I vos head of Gestapo for ten | Michael Palin (as Heinrich Bimmler)
years. Ah! Five years! Nein! No! | in: The North Minehead Bye-Election
Oh. Was NOT head of Gestapo AT ALL!" | (Monty Python's Flying Circus)

[John W. Krahn]

Jeff 'japhy' Pinyan wrote:

>
> On 6 Sep 2003, Researcher wrote:
>

> >I'm trying to create a code to count a certain character in a string,
> >lets say that I want to know how many letters "o" there are in the
> >text "The book is yellow", I'd use the following code:
> >
> >$text = "The book is yellow";
> >@characters = split (//,$text);
> >foreach $char (@characters){
> > if ($char eq "o"){
> > $count++;
> > }
> >}

>
> If you just want to count the number of times a character occurs in a
> string, use the tr/// operator.
>
> $o_count = $string =~ tr/o//;
>
> Read 'perldoc perlop' for more on tr///.

Or if 'o' is in a variable you can do this:

my $char = 'o';

$count = () = $string =~ /\Q$char/g;


John
--
use Perl;
program
fulfillment

[Gunnar Hjalmarsson]

Researcher wrote:

> I'm trying to create a code to count a certain character in a
> string, lets say that I want to know how many letters "o" there are
> in the text "The book is yellow",

<snip>

> what if I want to count a block of characters instead of one only
> (e.g. how many "el" there are in $text)?

This method works with both single characters and strings:

$text = "The book is yellow";
$count++ while $text =~ /o/g;

Btw, you asked a FAQ. This is where you should have looked up the
answer:

perldoc -q count

--
Gunnar Hjalmarsson
Email: [url]http://www.gunnar.cc/cgi-bin/contact.pl[/url]

[Greg]

Gunnar Hjalmarsson <noreply@gunnar.cc> wrote in message news:<bjdong$hp5o9$1@ID-184292.news.uni-berlin.de>...

> Researcher wrote:

> > I'm trying to create a code to count a certain character in a
> > string, lets say that I want to know how many letters "o" there are
> > in the text "The book is yellow",

>
> <snip>
>

> > what if I want to count a block of characters instead of one only
> > (e.g. how many "el" there are in $text)?

>
> This method works with both single characters and strings:
>
> $text = "The book is yellow";
> $count++ while $text =~ /o/g;
>
> Btw, you asked a FAQ. This is where you should have looked up the
> answer:
>
> perldoc -q count

Just as an alternative to the regex methods, a common way in some
languages of counting all the character types in a string would be to
use the character code as an array index:

my $text = "The book is yellow";
my @a;

$a[ord(lc $_)]++ for split(//, $text);

print $a[ord('o')], $/;


Not an expert, so FWIW.

[Anno Siegel]

Greg <gdsafford@hotmail.com> wrote in comp.lang.perl.misc:

> Gunnar Hjalmarsson <noreply@gunnar.cc> wrote in message
> news:<bjdong$hp5o9$1@ID-184292.news.uni-berlin.de>...

> > Researcher wrote:

> > > I'm trying to create a code to count a certain character in a
> > > string, lets say that I want to know how many letters "o" there are
> > > in the text "The book is yellow",

> >
> > <snip>
> >

> > > what if I want to count a block of characters instead of one only
> > > (e.g. how many "el" there are in $text)?

> >
> > This method works with both single characters and strings:
> >
> > $text = "The book is yellow";
> > $count++ while $text =~ /o/g;
> >
> > Btw, you asked a FAQ. This is where you should have looked up the
> > answer:
> >
> > perldoc -q count

>
> Just as an alternative to the regex methods, a common way in some
> languages of counting all the character types in a string would be to
> use the character code as an array index:

Those must be languages without a hash data type.

> my $text = "The book is yellow";
> my @a;
>
> $a[ord(lc $_)]++ for split(//, $text);
>
> print $a[ord('o')], $/;

In Perl, there is no need to decode the characters first:

my %a;
$a{ $_}++ for split //, $text;

print "$a{ o}\n";

Re-introduce the lc() if wanted.

Anno