AutoHotKey - test if string contains another string

In an .ahk script how can I test if a stri开发者_如何学Pythonng contains another string?

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From the autohotkey help file:

InStr(Haystack, Needle [, CaseSensitive = false, StartingPos = 1, Occurrence = 1]): Returns the position of an occurrence of the string Needle in the string Haystack. Unlike StringGetPos, position 1 is the first character; this is because 0 is synonymous with "false", making it an intuitive "not found" indicator. If the parameter CaseSensitive is omitted or false, the search is not case sensitive (the method of insensitivity depends on StringCaseSense); otherwise, the case must match exactly. If StartingPos is omitted, it defaults to 1 (the beginning of Haystack). Otherwise, specify 2 to start at Haystack's second character, 3 to start at the third, etc. If StartingPos is beyond the length of Haystack, 0 is returned. If StartingPos is 0 or negative, the search is conducted in reverse (right-to-left) beginning at that offset from the end. Regardless of the value of StartingPos, the returned position is always relative to the first character of Haystack. For example, the position of "abc" in "123abc789" is always 4. Specify 2 for Occurrence to return the position of the second match, 3 for the third match, etc. Related items: RegExMatch(), IfInString, and StringGetPos.