Merge pull request Light-City#75 from techkang/patch-2

Update 重要.cpp

practical_exercises/10_day_practice/day7/综合例题/重要.cpp

@@ -1,70 +1,91 @@
-//设计一个字符串类String，通过运算符重载实现字符串的输入、输出以及+=、==、!=、<、>、>=、[ ]等运算。
+//设计一个字符串类String，通过运算符重载实现字符串的输入、输出以及+=、==、!=、<、>、>=、[ ]等运算。
 #include <iostream>
 #include <cstring>
 using namespace std;
-class String {
+class String
+{
 private:
-int length;                     		//字符串长度
-char *sPtr;                     		//存放字符串的指针
-void setString( const char *s2);	
-friend ostream &operator<<(ostream &os, const String &s); 
-friend istream &operator>>(istream &is, String &s);  //重载输入运算符
+    int length; //字符串长度
+    char *sPtr; //存放字符串的指针
+    void setString(const char *s2);
+    friend ostream &operator<<(ostream &os, const String &s)
+    {
+        return os << s.sPtr;
+    };
+    friend istream &operator>>(istream &is, String &s)
+    {
+        return is >> s.sPtr;
+    }; //重载输入运算符
 public:
-    String( const char * = "" );                   
-    const String &operator=(const String &R); 		//重载赋值运算符 =
-    const String &operator+=(const String &R);		//字符串的连接 +=
-    bool operator==(const String &R);				//字符串的相等比较 ==
-    bool operator!=(const String &R);				//字符串的不等比较 !=
-    bool operator!() ;               				//判定字符串是否为空
-    bool operator<(const String &R) const;     		//字符串的小于比较 <
-    bool operator>(const String &R);                	//字符串的大于比较 >
-    bool operator>=(const String &R);             	//字符串的大于等于比较
-    char &operator[](int);                         	//字符串的下标运算
-    ~String();  
+    String(const char * = "");
+    const String &operator=(const String &R)
+    {
+        length = R.length;
+        strcpy(R.sPtr, sPtr);
+        return *this;
+    };                                         //重载赋值运算符 =
+    const String &operator+=(const String &R); //字符串的连接 +=
+    bool operator==(const String &R);          //字符串的相等比较 ==
+    bool operator!=(const String &R);          //字符串的不等比较 !=
+    bool operator!();                          //判定字符串是否为空
+    bool operator<(const String &R) const;     //字符串的小于比较 <
+    bool operator>(const String &R);           //字符串的大于比较 >
+    bool operator>=(const String &R);          //字符串的大于等于比较
+    char &operator[](int);                     //字符串的下标运算
+    ~String(){};
 };
-const String &String::operator+=(const String &R) {
-    char *temp = sPtr;              
-    length += R.length;           
-    sPtr = new char[length+1]; 
-    strcpy(sPtr,temp );           
-    strcat(sPtr,R.sPtr );         
-    delete [] temp;                 
-    return *this;                         
+const String &String::operator+=(const String &R)
+{
+    char *temp = sPtr;
+    length += R.length;
+    sPtr = new char[length + 1];
+    strcpy(sPtr, temp);
+    strcat(sPtr, R.sPtr);
+    delete[] temp;
+    return *this;
 }
-bool String::operator==(const String &R){return strcmp(sPtr,R.sPtr)==0;}
-bool String::operator!=(const String & R){return !(*this==R);}
-bool String::operator!(){return length ==0;}
-bool String::operator<(const String &R)const{return strcmp(sPtr,R.sPtr)<0;}
-bool String::operator>(const String &R){return R<*this;}
-bool String::operator>=(const String &R){return !(*this<R);}
-char &String::operator[](int subscript){return sPtr[subscript];}
-int main(){
-    String s1("happy"),s2("new year"),s3;
-    cout << "s1 is " << s1 << "\ns2 is " << s2 << "\ns3 is " << s3       
-    << "\n比较s2和s1:"
-    << "\ns2 ==s1结果是 " << ( s2 == s1 ? "true" : "false")
-    << "\ns2 != s1结果是 " << ( s2 != s1 ? "true" : "false")
-    << "\ns2 >  s1结果是 " << ( s2 >  s1 ? "true" : "false") 
-    << "\ns2 <  s1结果是 " << ( s2 <  s1 ? "true" : "false") 
-    << "\ns2 >= s1结果是 " << ( s2 >= s1 ? "true" : "false");
-    cout << "\n\n测试s3是否为空: ";                         	
-    if (!s3){
-        cout << "s3是空串"<<endl;                           	//L3
-        cout<<"把s1赋给s3的结果是：";                    		       	
-        s3 = s1;                                         
-        cout << "s3=" << s3 << "\n";                          	//L5
+String::String(const char *str)
+{
+    sPtr = new char[strlen(str) + 1];
+    strcpy(sPtr, str);
+    length = strlen(str);
+};
+bool String::operator==(const String &R) { return strcmp(sPtr, R.sPtr) == 0; }
+bool String::operator!=(const String &R) { return !(*this == R); }
+bool String::operator!() { return length == 0; }
+bool String::operator<(const String &R) const { return strcmp(sPtr, R.sPtr) < 0; }
+bool String::operator>(const String &R) { return R < *this; }
+bool String::operator>=(const String &R) { return !(*this < R); }
+char &String::operator[](int subscript) { return sPtr[subscript]; }
+int main()
+{
+    String s1("happy"), s2("new year"), s3;
+    cout << "s1 is " << s1 << "\ns2 is " << s2 << "\ns3 is " << s3
+         << "\n比较s2和s1:"
+         << "\ns2 ==s1结果是 " << (s2 == s1 ? "true" : "false")
+         << "\ns2 != s1结果是 " << (s2 != s1 ? "true" : "false")
+         << "\ns2 >  s1结果是 " << (s2 > s1 ? "true" : "false")
+         << "\ns2 <  s1结果是 " << (s2 < s1 ? "true" : "false")
+         << "\ns2 >= s1结果是 " << (s2 >= s1 ? "true" : "false");
+    cout << "\n\n测试s3是否为空: ";
+    if (!s3)
+    {
+        cout << "s3是空串" << endl; //L3
+        cout << "把s1赋给s3的结果是：";
+        s3 = s1;
+        cout << "s3=" << s3 << "\n"; //L5
     }
-    cout << "s1 += s2 的结果是：s1=";                      	//L6
-    s1 += s2;                                       
-    cout << s1;                                             		//L7
-                                                        
-    cout << "\ns1 +=  to you 的结果是：";                     	//L8
-    s1 += " to you";                               
-    cout << "s1 = " << s1 <<endl;                              	//L9
-    s1[0] = 'H';      
+    cout << "s1 += s2 的结果是：s1="; //L6
+    s1 += s2;
+    cout << s1; //L7
+
+    cout << "\ns1 +=  to you 的结果是："; //L8
+    s1 += " to you";
+    cout << "s1 = " << s1 << endl; //L9
+    s1[0] = 'H';
     s1[6] = 'N';
     s1[10] = 'Y';
-    cout << "s1 = " << s1 << "\n";                               //L10
+    cout << "s1 = " << s1 << "\n"; //L10
     system("pause");
     return 0;
 }