int toupper(int c)

Returns the uppercase version of c. If c is not an ASCII letter, it is returned unchanged.

To change the case of a whole string, use StrToUpper.

toupper('a') -> 'A'
toupper('A') -> 'A'
toupper('/') -> '/' // not a letter
toupper('ä') -> 'ä' // non-ASCII character

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