actually, it matches also =>, <>, !!, <=>, or in fact any combination of these four characters. It says "match these characters, one or more times".
If you want only one of the 4 characters followed by a single "=", you'd write [!<=>]=

In reply to Re^4: How to extract special characters like <=, >= != from string by soonix
in thread How to extract special charachetrs like <=, >= != from string by gjoshi

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