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counting occurence(s)

Posted on 2003-10-26
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Last Modified: 2010-03-04
I've got 2 variables named $one and $two.
$one contains a whole sentence, for example:

$one="The cat is never far from home";

$two contains some characters, for example:

$two="The e o";

Now I want to count the occurences of each character/word of $two in $one.
For example:
'The' should give as result 1, because the word The occures one time in $one
'e' should give as result 3, because the character 'e' occures three times in $one
'o' should give a result 2, because the character 'o' occures two times in $one

Which lines do I need for this ?
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Question by:michael123199
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jmcg earned 25 total points
ID: 9625033
I would think you'd need two different approaches depending on whether the thing you were looking to count was a word or a character.

For characters, the tr/// operator is the one usually suggested. It returns a count of characters transliterated, even if you transliterate a particular letter into itself.

$lettercount = $one =~ tr/e/e/;

which places the value 4 in $lettercount (not 3 as you counted).

For words, there are two ways I can see to go. One is to use a regular expression match, possibly decorating the word to be found with \b delimiters to ensure that we do not find a word that appears embedded in another word (e.g. "pear" in "appears"). The other approach would be to split up the $one string and count how many times each word in it occurs (possibly arranging to lower-case words that are capitalized as we go along).

$counts{lc $_}++ foreach split /\W+/, $one;

Then, for the words in your list, the value of $counts{lc $word} can be directly accessed from the hash.

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