This has already been covered in other posts, but this may clarify things for Wassercrats.
If you don't scope your variables, it is not immediately obvious whether:
1) You variables will have changed by calling a sub.
2) If the variables did change, whether they were changed on purpose, or accidently.
$x = 0;
DoStuffX();
print "As long as no one used global variables, I know that x = 0 ",
"without needing to know what DoStuffX does.\n";
if ($x != 0) { print "Nope, I need to spend time looking through ",
"DoStuffX to find out why x changed. I really ",
"wish the guy used \$x=DoStuffX(\$x) so that I ",
"would know whether he changed x intensionally ",
"or not.\n\n" };
$y = 0;
DoStuffY($y);
print "As long as no one used global variables, I know that y = 0 ",
"without needing to know what DoStuffY does.\n";
if ($y == 0) { print "Yippie! I can go home early!\n\n" };
sub DoStuffX {
# lost of code involving $x
$x=$x+1;
# lots of code involving $x
};
sub DoStuffY {
my $y = shift @_;
# lost of code involving $y
$y=$y+1;
# lots of code involving $y
};
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