+/* Returns true for lowercase letters in the "C" locale.
+ In any other locale, also returns true for a locale-specific set of
+ characters which are neither control characters, digits, punctation, or
+ space (' '). In a locale other than the "C" locale, a character might test
+ true for both islower() and isupper().
+*/
+int islower( int c ) _PDCLIB_nothrow;
+
+/* Returns true for every printing character including space (' '). */
+int isprint( int c ) _PDCLIB_nothrow;
+
+/* Returns true for every printing character that is neither whitespace
+ nor alphanumeric in the "C" locale. In any other locale, there might be
+ characters that are printing characters, but neither whitespace nor
+ alphanumeric.
+*/
+int ispunct( int c ) _PDCLIB_nothrow;
+
+/* Returns true for every standard whitespace character (' ', '\f', '\n', '\r',
+ '\t', '\v') in the "C" locale. In any other locale, also returns true for a
+ locale-specific set of characters for which isalnum() is false.
+*/
+int isspace( int c ) _PDCLIB_nothrow;
+
+/* Returns true for uppercase letters in the "C" locale.
+ In any other locale, also returns true for a locale-specific set of
+ characters which are neither control characters, digits, punctation, or
+ space (' '). In a locale other than the "C" locale, a character might test
+ true for both islower() and isupper().
+*/
+int isupper( int c ) _PDCLIB_nothrow;