1 files changed, 28 insertions, 0 deletions
diff --git a/src/string/strspn.c b/src/string/strspn.c
new file mode 100644
index 00000000..e67461a5
--- /dev/null
+++ b/src/string/strspn.c
@@ -0,0 +1,28 @@
+#include <string.h>
+#include "nonstd/assert.h"
+
+/** count matching characters **/
+size_t strspn(const char *s1, const char *s2)
+{
+	size_t i = 0;
+
+	ASSERT_NONNULL(s1);
+	ASSERT_NONNULL(s2);
+
+	for (i = 0; i < strlen (s1); i++) {
+		if (strchr(s2, s1[i]) == NULL) {
+			break;
+		}
+	}
+
+	return i;
+}
+
+/***
+computes the length of the maximum initial segment of the ARGUMENT(s1) made
+up of characters from ARGUMENT(s2).
+***/
+/*
+	RETURN_ALWAYS(the number of matching characters);
+STDC(1)
+*/