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# Perl4:

    7.375039999999996141
    7.37503999999999614

# Perl5:

    7.373504
    7.37503999999999614

#############################################################################
# Example 32 - Submitted by Danny Faught
#############################################################################
# perl 4 lets you modify constants:

    $foo = "x";
    &mod($foo);
    for ($x = 0; $x < 3; $x++) {
	&mod("a");
    }
    sub mod {
	print "before: $_[0]";
	$_[0] = "m";
	print "  after: $_[0]\n";
    }

# perl4 output:
    before: x  after: m
    before: a  after: m
    before: m  after: m
    before: m  after: m

# perl5 output:
    before: x  after: m
    Modification of a read-only value attempted at foo.pl line 12.
    before: a

#############################################################################
# Example 33 - Submitted by Danny Faught
#############################################################################
Just a quick note to say that localizing @_ has always been broken
in perl5 (especially where defgv is involved in other guises).  Try
this from my 5.001m collection (I don't believe I ever took the time
to report this :-()

     for (1..10) { print "Trial $_\n"; &foo('a', 'b', 'c') }
     sub foo { local(@_) = ('p', 'q', 'r'); }

# This problem will be fixed in 5.003 - Bill

#############################################################################
# Example 34 - Noted in c.l.p.misc by Maurice Cinquini 
#############################################################################
I've even come across old perl4 programs which
unconsciously rely on the bugs in earlier perl versions.

    perl -e '$bar=q/not/; print "This is $foo{$bar} perl5"'

# perl4 prints: This is not perl5
# perl4 prints: This is perl5

#############################################################################
# Example 35 - Submitted by Markus F.X.J. Oberhumer and Danny Faught
#############################################################################
# Stricter parsing of variables used in regular expressions

        s/^([^$grpc]*$grpc[$opt$plus$rep]?)//o;

# perl4: compiles w/o error
# perl5: with Scalar found where operator expected ..., near "$opt$plus"

# an added component of this example, apparantly from the same script, is
# the actual value of the s'd string after the substitution, e.g. - 

    $grpc   = '\)'; 
    $opt    = '\?';
    $plus = '\+';
    $rep  = '\*';
    $_ = 'foo)?';
    s/^([^$grpc]*${grpc}[$opt]?)/bar/;
    print ;

# perl4 prints: bar
# perl5 prints: barfoo)?

#############################################################################
# Example 36 - Submitted by Kenneth Albanowski from Eric Hendrickson
#############################################################################
# Under perl5, m?x? matches only once, like ?x?. Under perl4, it matched
# repeatedly, like /x/ or m!x!.

    $test = "once";
    sub match { $test =~ m?once?; }
    &match();
    if ( &match() ) {
        # m?x? matches more then once
        print "perl4\n";
    } else {
        # m?x? matches only once
        print "perl5\n";
    }

# perl4 prints: perl4
# perl5 prints: perl5

#############################################################################
# Example 37 - Submitted by Jerry Whelan
#############################################################################
# parsing; note the space between . and =

    $string . = "more string";
    print $string;

# perl4 prints: more string
# perl5 prints: syntax error at - line 1, near ". ="

#############################################################################
# Example 38 - Submitted by Danny Faught
#############################################################################
# The behavior is slightly different for: