How do I convert a string to all upper or lower case?

Q

How do I convert a string to all upper or lower case?

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A

Some libraries have routines strupr and strlwr or strupper and strlower, but these are not Standard or portable. It's a straightforward exercise to write upper/lower-case functions in terms of the toupper and tolower macros in <ctype.h>;(The only tricky part is that the function will either have to modify the string in-place or deal with the problem of returning a new string;
(Note also that converting characters and strings to upper or lower case is vastly more complicated when multinational character sets are being used.)

2015-08-19, 860👍, 0💬