1 files changed, 29 insertions, 0 deletions
diff --git a/src/ctype/iscntrl.c b/src/ctype/iscntrl.c
new file mode 100644
index 00000000..31804123
--- /dev/null
+++ b/src/ctype/iscntrl.c
@@ -0,0 +1,29 @@
+#include <ctype.h>
+#include "limits.h"
+#include "nonstd/assert.h"
+#include "nonstd/ctype.h"
+#include "nonstd/internal.h"
+
+/** test whether a character is a control character */
+int iscntrl(int c)
+{
+	unsigned int *map = __libc(CTYPE);
+
+	ASSERT_REPRESENTABLE(c, 0, UCHAR_MAX, unsigned char, EOF);
+	/*
+	RETURN(NONZERO, ARGUMENT(c) is a control character);
+	RETURN(0, ARGUMENT(c) is not a control character);
+	*/
+
+	return map[c] == 0 || (map[c] == SPACE && c != ' ');
+}
+
+/***
+tests whether ARGUMENT(c) is a character in the class CHARACTER_CLASS(cntrl) in the
+current locale.
+***/
+
+/*
+LC_CTYPE
+STDC(1)
+*/