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run code in 150+ php & hhvm versions
Bugs & Features
<?php function do_split($name) { return preg_split('/([A-Z]{2,}|([A-Z][^A-Z]*))/', $name, null, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY); } function convert_case($name) { return implode( '_', array_map( 'strtolower', do_split($name) ) ); } function convert_case2($name) { $length = strlen($name); if ($length < 2) { return strtolower($name); } $output = ''; // init stream $prev_val = '_'; $prev_upr = false; $char_val = $name[0]; $char_upr = ctype_upper($char_val); for ($i = 0; $i < $length; $i++) { // peek $next_val = $i+1 < $length ? $name[$i+1] : '_'; $next_upr = ctype_upper($next_val); if ($prev_val == '_') { if ($char_val == '_') { continue; } $output .= $char_val; } else if ($char_upr !== $prev_upr) { $output .= '_'.$char_val; } else if ($char_upr && !$next_upr) { // && $prev_upr if ($prev_upr) { $output .= '_'.$char_val; $char_upr = false; } else { $output .= $char_val; } } else { $output .= $char_val; } // roll over $prev_val = $char_val; $prev_upr = $char_upr; $char_val = $next_val; $char_upr = $next_upr; } return strtolower($output); } convert_case2('FooBARbar0123'); $samples = array( 'FooBar', 'FooBAR', 'FOOBar', 'foo_bar', 'FOO_bar', 'FOO_Bar', 'foo_BAR', 'foo_Bar', 'Foo_bar', ); print_r(array_map(function ($name) { return array( 'name' => $name, 'converted' => convert_case2($name), // 'converted' => convert_case($name), ); }, $samples));
based on gdP9C
Output for 5.3.0 - 5.6.28, hhvm-3.10.0 - 3.13.2, 7.0.0 - 7.1.0
Array ( [0] => Array ( [name] => FooBar [converted] => f_oo_b_ar ) [1] => Array ( [name] => FooBAR [converted] => f_oo_ba_r ) [2] => Array ( [name] => FOOBar [converted] => foo_bar ) [3] => Array ( [name] => foo_bar [converted] => foo_bar ) [4] => Array ( [name] => FOO_bar [converted] => fo_o_bar ) [5] => Array ( [name] => FOO_Bar [converted] => fo_o_b_ar ) [6] => Array ( [name] => foo_BAR [converted] => foo_ba_r ) [7] => Array ( [name] => foo_Bar [converted] => foo_b_ar ) [8] => Array ( [name] => Foo_bar [converted] => f_oo_bar ) )
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.2.17
Parse error: syntax error, unexpected T_FUNCTION, expecting ')' in /in/n9NrJ on line 74
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.4.1, 5.0.0 - 5.0.5
Parse error: parse error, unexpected T_FUNCTION, expecting ')' in /in/n9NrJ on line 74
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error, expecting `')'' in /in/n9NrJ on line 74
Process exited with code 255.