1 files changed, 43 insertions, 0 deletions
diff --git a/libc/ctype/islower.c b/libc/ctype/islower.c
new file mode 100644
index 0000000..81ad0bb
--- /dev/null
+++ b/libc/ctype/islower.c
@@ -0,0 +1,43 @@
+
+/*
+FUNCTION
+<<islower>>---lower-case character predicate
+
+INDEX
+islower
+
+ANSI_SYNOPSIS
+#include <ctype.h>
+int islower(int <[c]>);
+
+TRAD_SYNOPSIS
+#include <ctype.h>
+int islower(<[c]>);
+
+DESCRIPTION
+<<islower>> is a macro which classifies ASCII integer values by table
+lookup.  It is a predicate returning non-zero for minuscules
+(lower-case alphabetic characters), and 0 for other characters.
+It is defined only when <<isascii>>(<[c]>) is true or <[c]> is EOF.
+
+You can use a compiled subroutine instead of the macro definition by
+undefining the macro using `<<#undef islower>>'.
+
+RETURNS
+<<islower>> returns non-zero if <[c]> is a lower case letter (<<a>>--<<z>>).
+
+PORTABILITY
+<<islower>> is ANSI C.
+
+No supporting OS subroutines are required.
+*/
+#include <_ansi.h>
+#include <ctype.h>
+
+#undef islower
+int
+_DEFUN(islower,(c),int c)
+{
+	return((_ctype_ + 1)[c] & _L);
+}
+