// This code is Public Domain. Use, modify, and redistribute at will.
// ----------------------------------------------------------------------------
-// ----------------------------------------------------------------------------
-// C++
-
-const char * strstr( const char * s1, const char * s2 ) { /* TODO */ };
-char * strstr( char * s1, const char * s2 ) { /* TODO */ };
-
-// ----------------------------------------------------------------------------
-// Standard C
+#include <__NULL.h>
-char * strstr( const char * s1, const char * s2 ) { /* TODO */ };
+char * strstr( const char * src_1, const char * src_2 )
+{
+ const char * p1 = src_1;
+ const char * p2;
+ while ( *src_1 != '\0' )
+ {
+ p2 = src_2;
+ while ( ( *p2 != '\0' ) && ( *p1 == *p2 ) )
+ {
+ ++p1;
+ ++p2;
+ }
+ if ( *p2 == '\0' )
+ {
+ return (char *) src_1;
+ }
+ ++src_1;
+ p1 = src_1;
+ }
+ return NULL;
+}