Added include guards

Stopwatch.h

@@ -5,6 +5,10 @@
 //This struct helps by using a struct to simplify timing a program in C
 
 
+#ifndef STOPWATCH_H
+#define STOPWATCH_H
+
+
 #include <time.h>
 #include <inttypes.h>
 #include <stdio.h>
@@ -134,4 +138,7 @@ char* getStr(struct Stopwatch* timer){
 	}
 
 	return num;
-}
+}
+
+
+#endif //STOPWATCH_H