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