+#ifndef __HAVE_ARCH_STRCSPN
+/**
+ * strcspn - Calculate the length of the initial substring of @s which does
+ * not contain letters in @reject
+ * @s: The string to be searched
+ * @reject: The string to avoid
+ */
+size_t strcspn(const char *s, const char *reject)
+{
+ const char *p;
+ const char *r;
+ size_t count = 0;
+
+ for (p = s; *p != '\0'; ++p) {
+ for (r = reject; *r != '\0'; ++r) {
+ if (*p == *r)
+ return count;
+ }
+ ++count;
+ }
+ return count;
+}
+#endif
+