How to count the number of "a" occurencies in a string ?

[Pete Sammet]

Sorry for this newbie question:

Is there a function in Perl for counting the number of e.g. "a" in a String ?

For example:

$num = countchars("abbbabbbaba", 'a');

should yield 4. Unfortunately the function "countchars" does not exist.

is there another one-liner function ?

Another realted but more advanced question:
Is there a counter function for counting INDEPENDENT "a" in a String?
In this case concatenated "a" should be counted as 1. e.g.

$num = countcharschains("aammmammaaaaam", 'a');

Should yield 3

Pete

 

[Peter Makholm]

$num = countchars("abbbabbbaba", 'a');

should yield 4. Unfortunately the function "countchars" does not exist.

Yes it does, it is called tr///

makholm@makholm:/tmp$ perl -le '$foo = "abbbabbbaba"; print ($foo =~ y/a//); print $foo'
4
abbbabbbaba
makholm@makholm:/tmp$

Is there a counter function for counting INDEPENDENT "a" in a String?
In this case concatenated "a" should be counted as 1. e.g.

$num = countcharschains("aammmammaaaaam", 'a');

Should yield 3

scalar( ()= "aammmammaaaaam" =~ m/a+/g );

//Makholm

 

[Gunnar Hjalmarsson]

Is there a function in Perl for counting the number of e.g. "a" in a String ?

For example:

$num = countchars("abbbabbbaba", 'a');

should yield 4. Unfortunately the function "countchars" does not exist.

is there another one-liner function ?

No, but there is an applicable FAQ entry.

perldoc -q count.+string

Another realted but more advanced question:
Is there a counter function for counting INDEPENDENT "a" in a String?
In this case concatenated "a" should be counted as 1. e.g.

$num = countcharschains("aammmammaaaaam", 'a');

Should yield 3

Same FAQ.

 

[Jürgen Exner]

Is there a function in Perl for counting the number of e.g. "a" in a
String ?
$num = countchars("abbbabbbaba", 'a');
should yield 4. Unfortunately the function "countchars" does not
exist.

perldoc -f tr
tr/SEARCHLIST/REPLACEMENTLIST/cds
Transliterates all occurrences of the characters found in the
search list with the corresponding character in the replacement
list. It RETURNS THE NUMBER OF CHARACTERS REPLACED OR DELETED.

my $foo = "abbbabbbaba";
print ($foo =~ tr/a/a/);

Another realted but more advanced question:
Is there a counter function for counting INDEPENDENT "a" in a String?
In this case concatenated "a" should be counted as 1. e.g.

$num = countcharschains("aammmammaaaaam", 'a');

Should yield 3

perldoc -f s:
s/PATTERN/REPLACEMENT/egimosx
Searches a string for a pattern, and if found, replaces that
pattern with the replacement text AND RETURNS THE NUMBER OF
SUBSTITUTIONS MADE.

jue