使用preg_replace_callback将数字大写在数字后面

I want to convert a pattern like "5a " into "5A ". This pattern may appear at the beginning or middle of a larger string. I've tried this:

我想将像“5a”这样的模式转换为“5A”。此模式可能出现在较大字符串的开头或中间。我试过这个：

$string = preg_replace_callback("/(0-9)([a-z]) /", function($matches) {
  return $matches[1].strtoupper($matches[2]).' ';
}, $string);

But it doesn't work. No error - the string just stays as "5a ". Can you see where I've gone wrong?

但它不起作用。没有错误 - 字符串只是保持为“5a”。你能看出我出错的地方吗？

1 个解决方案

#1

/(0-9)([a-z]) /

should be

应该

/([0-9])([a-z]) /