islower() ctype Macro (ctype.h) islower() Check if a character is a lower-case letter #include <ctype.h> int islower(c) int c; islower tests whether the argument c is a lower-case letter (a-z). It returns a number other than zero if c is is a lower- case letter, and zero if it is not. islower assumes that c is an ASCII character or EOF. ***** Example ***** For an example of how to use this macro, see the entry for ctype. ***** See Also ***** ASCII, ctype COHERENT Lexicon Page 1