in reply to Logical Assignment Op (with Spreadsheet::ParseExcel)

The ||= performs an assignment only when the lvalue is false. "$x ||= $y" is equivalent to "if ( ! $x ) { $x = $y }".

In this case, if $sheet->{MaxRow} doesn't have a non-zero value, it takes the value of $sheet->{MinRow}.

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Re^2: Logical Assignment Op (with Spreadsheet::ParseExcel)
by FunkyMonk (Bishop) on May 17, 2007 at 21:49 UTC
    In this case, if $sheet->{MaxRow} doesn't have a non-zero value, it takes the value of $sheet->{MinRow}.
    But beware, Perl has a wider view of what constitutes a false value. The following values are all false:
    • undef
    • 0 (either as a number or string)
    • "" (the empty string)
    Everything else is true. This means that values such as "0.0" or "0e00" are true, not false.

    print "undef  is ", ( undef  ) ? "true\n" : "false\n";
print "0      is ", ( 0      ) ? "true\n" : "false\n";
print "'0'    is ", ( '0'    ) ? "true\n" : "false\n";
print "''     is ", ( ''     ) ? "true\n" : "false\n";
print "' '    is ", ( ' '    ) ? "true\n" : "false\n";
print "'0.0'  is ", ( '0.0'  ) ? "true\n" : "false\n";
print "'0e00' is ", ( '0e00' ) ? "true\n" : "false\n";
__DATA__
undef  is false
0      is false
'0'    is false
''     is false
' '    is true
'0.0'  is true
'0e00' is true

    [download]

    I don't know the specifics of Spreadsheet::ParseExcel, so this may not relevant ;)

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