Merge pull request Mooophy#446 from Soyn/master

fix

ch13/ex13_08.h

@@ -7,7 +7,7 @@
 //  Write the assignment operator for the HasPtr class from exercise 13.5 in 13.1.1 (p. 499).
 //  As with the copy constructor, your assignment operator should copy the object to which ps points.
 //
-//  See ex13_05.h 
+//  See ex13_05.h
 
 #ifndef CP5_ex13_08_h
 #define CP5_ex13_08_h
@@ -18,11 +18,13 @@ class HasPtr {
 public:
     HasPtr(const std::string &s = std::string()) : ps(new std::string(s)), i(0) { }
     HasPtr(const HasPtr &hp) : ps(new std::string(*hp.ps)), i(hp.i) { }
-    HasPtr& operator=(const HasPtr &hp) {
-        std::string *new_ps = new std::string(*hp.ps);
-        delete ps;
-        ps = new_ps;
-        i = hp.i;
+    HasPtr& operator=(const HasPtr &rhs_hp) {
+        if(this != &rhs_hp){
+            std::string *temp_ps = new std::string(*rhs_hp.ps);
+            delete ps;
+            ps = temp_ps;
+            i = rhs_hp.i;
+        }
         return *this;
     }
 private: