tr doesn't take character classes in square brackets ([]), so your code can also be written as:

if (0 == $s =~ tr/IOSM//c) {

[download]

Your code counts whether there is any of the letters I, O, S or M in the string. Which is obviously true.

Maybe you wanted to match the letters in order?

m/I+O+S+M+/

[download]

In reply to Re: Pattern matching regex problem by Corion
in thread Pattern matching regex problem by Anonymous Monk

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