1 files changed, 51 insertions, 0 deletions
diff --git a/src/pdclib/functions/string/strstr.c b/src/pdclib/functions/string/strstr.c
new file mode 100644
index 0000000..aee282f
--- /dev/null
+++ b/src/pdclib/functions/string/strstr.c
@@ -0,0 +1,51 @@
+/* strstr( const char *, const char * )
+
+   This file is part of the Public Domain C Library (PDCLib).
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#include <string.h>
+
+#ifndef REGTEST
+
+char * strstr( const char * s1, const char * s2 )
+{
+    const char * p1 = s1;
+    const char * p2;
+    while ( *s1 )
+    {
+        p2 = s2;
+        while ( *p2 && ( *p1 == *p2 ) )
+        {
+            ++p1;
+            ++p2;
+        }
+        if ( ! *p2 )
+        {
+            return (char *) s1;
+        }
+        ++s1;
+        p1 = s1;
+    }
+    return NULL;
+}
+
+#endif
+
+#ifdef TEST
+
+#include "_PDCLIB_test.h"
+
+int main( void )
+{
+    char s[] = "abcabcabcdabcde";
+    TESTCASE( strstr( s, "x" ) == NULL );
+    TESTCASE( strstr( s, "xyz" ) == NULL );
+    TESTCASE( strstr( s, "a" ) == &s[0] );
+    TESTCASE( strstr( s, "abc" ) == &s[0] );
+    TESTCASE( strstr( s, "abcd" ) == &s[6] );
+    TESTCASE( strstr( s, "abcde" ) == &s[10] );
+    return TEST_RESULTS;
+}
+
+#endif