in reply to Perl 5.16 fc()

First is false, second is true.
perl -Mutf8 -E'say lc(uc("\N{LATIN CAPITAL LETTER SHARP S}")) eq lc(uc("SS"))' perl -Mutf8 -E'say fc("\N{LATIN CAPITAL LETTER SHARP S}") eq fc("SS")'

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Re^2: Perl 5.16 fc()
by ikegami (Patriarch) on May 22, 2012 at 20:05 UTC
    LATIN CAPITAL LETTER SHARP S
    uc("ẞ") ⇒ "ẞ"   (LATIN CAPITAL LETTER SHARP S)
    lc("ẞ") ⇒ "ß"   (LATIN SMALL LETTER SHARP S)
    fc("ẞ") ⇒ "ss"
    
    LATIN SMALL LETTER SHARP S
    uc("ß") ⇒ "SS"  ←
    lc("ß") ⇒ "ß"   (LATIN SMALL LETTER SHARP S)
    fc("ß") ⇒ "ss"
    
    uc("SS") ⇒ "SS"
    lc("SS") ⇒ "ss"
    fc("SS") ⇒ "ss"
    
    uc("ss") ⇒ "SS"
    lc("ss") ⇒ "ss"
    fc("ss") ⇒ "ss"
    

    If you reverse the uc and the lc, the two expressions will be equivalent for this example, but I don't know if it holds for all cases, and it's not something you should count on.

Re^2: Perl 5.16 fc()
by OlegG (Monk) on May 22, 2012 at 11:00 UTC
    Really, thanks