从字符串中删除某些字符的重复项 [英] Remove duplicates of certain characters from string
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问题描述
仅在字符串$b
中相邻时,如何才能从字符串$b
中删除在数组$a
中找到的重复字符?
How could I remove duplicates of characters found in array $a
from string $b
only if they are found next to each other?
$a = array("a","b","c");
$b = "aabcccdef";
输出应为
abcdef
可以使用正则表达式找到字符,但是我不知道如何检测字符是否相邻.
Characters can be found with a regex but I have no idea how to detect if the characters are next to each other.
推荐答案
preg_replace( array('/a+/','/b+/','/c+/'),array('a','b','c',), $b );
另一种更为详尽的方法可能是:
Another way pretty more elaborate could be:
preg_replace_callback('/(\w+)/', function ($matches) use ($a) {
if ( in_array($matches[1][0],$a) ) //> if you need UTF-8 working use mb_substr here
return $matches[1][0];
},$b);
//> both untested
另一种旧方法(在一些字符字符串上可能会更快一些):
Another way, old way (that could be a bit faster on few chars string):
$c = '';
$cache = false;
for ($i=0;$i<strlen($b);$i++) {
$char = $b[$i];
if ($char !== $cache || !in_array($char,$a))
$c .= $char;
$cache=$char;
}
echo $c;
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