PHP - all combinations of upper and lower case characters of a string
I am trying to get all combinations of upper and lower case characters of a string. For example my string abc
. I need to get a result like this: all combinations for three characters of the string (2^0) x (2^1) x (2^2) = 8
::
abc
Abc
ABc
ABC
aBC
abC
AbC
aBc
My code is this, but I have a problem, my code has duplicate cases and does not return abc
and abc
:
<?php
function opposite_case($str)
{
if(ctype_upper($str))
{
return strtolower($str);
}
else
{
return strtoupper($str);
}
}
$str = "abc";
for($i = 0 ; $i < strlen($str) ; $i++)
{
for($j = 0 ; $j < strlen($str) ; $j++)
{
$str[$j] = opposite_case($str[$j]);
echo $str."<br>";
}
}
?>
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1 answer
A bit about the code dump with some comments added for a good estimate. This was converted from Java implementation - fooobar.com/questions/759381 / ...
http://sandbox.onlinephpfunctions.com/code/000e55236510216aa499dc54e092c94853f82b00
<?php
function calculatePermutations($text) {
$permutations = array();
$chars = str_split($text);
// Count the number of possible permutations and loop over each group
for ($i = 1; $i < strlen($text) ** 2; $i++) {
// Loop over each letter [a,b,c] for each group and switch its case
for ($j = 0; $j < strlen($text); $j++) {
// isBitSet checks to see if this letter in this group has been checked before
// read more about it here: http://php.net/manual/en/language.operators.bitwise.php
$permutations[$i][] = (isBitSet($i, $j))
? strtoupper($chars[$j])
: $chars[$j];
}
}
return $permutations;
}
function isBitSet($n, $offset) {
return ($n >> $offset & 1) != 0;
}
print_r(calculatePermutations('abc'));
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