Re: replace a digit with another digit

You're on the right path with tr.

$a = "A1";
$b = "B2";

printf("a: %s b: %s\n", $a, $b);

$a =~ tr/[12]/[21]/;
$b =~ tr/[12]/[21]/;

printf("a: %s b: %s\n", $a, $b);
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Comment on Re: replace a digit with another digit Download Code

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Re^2: replace a digit with another digit by davido (Cardinal) on Aug 17, 2005 at 19:21 UTC
`tr///` is ok if it doesn't matter whether or not the digit follows an alpha character. He didn't specify whether this would be an issue or not; his discription of the problem was inadequate at explaining whether the alpha character plays a significant roll in determining whether or not to swap twos for ones and ones for twos. Your example with `tr/[12]/[21]/;` is in error, though. Technically it's not hurting anything to be substituting a `[` character for another `[` character, but it's pointless to do so. You might have been thinking that you needed to set up a character class within the tr/// operator. But tr/// doesn't use character classes, so `[` and `]` are seen as literal characters to be transliterated. It's also advisable to get in the habit of not using `$a` and `$b`, even in examples, since these variables (their global form) play a crucial role in sort. In the interest of avoiding confusion or difficult to track-down bugs, let sort have $a and $b. You can have your way with $c .. $z though. ;) Dave	[reply] [d/l] [select]
Re^3: replace a digit with another digit by cowboy (Friar) on Aug 17, 2005 at 19:30 UTC
Agree'd on the $a/$b, and I see the point on the substitution. Thanks.	[reply]