Question

Lets say there is a string like:

A quick brOwn FOX called F. 4lviN

The WORDS i want TO SEARCH must have the following conditions:

• The words containing MIXED Upper & Lower Cases
• Containing ONLY alphabets A to Z (A-Z a-z)
  (e.g: No numbers, NO commas, NO full-stops, NO dash .. etc)

So suppose, when i search (for e.g in this string), the search result will be:

brOwn

Because it is the only word which contains both of Upper & Lower Case letters inside (and also containing only alphabets).

So how can I make it work in php?

Answer 1

You should be good with:

preg_match_all("/\b([a-z]+[A-Z]+[a-zA-Z]*|[A-Z]+[a-z]+[a-zA-Z]*)\b/", $input, $matches);
print_r($matches[1]); 

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Edit: As capturing is not needed, it can be also >>

preg_match_all("/\b(?:[a-z]+[A-Z]+[a-zA-Z]*|[A-Z]+[a-z]+[a-zA-Z]*)\b/", $input, $matches);
print_r($matches[0]);