由重载函数学习c++ (2)

来源：互联网发布：dr.com mac 编辑：程序博客网时间：2024/06/18 03:55

#include <iostream>#include <cstring>using namespace std;class String{public:String(){p=NULL;}String( char *str);friend bool operator >(String &string1,String &string2);friend bool operator <(String &string1,String &string2);friend bool operator ==(String &string1,String &string2);void display();private: char *p;};String::String( char *str){p=str;}void String::display(){cout<<p;//输出p所指向的字符串}bool operator>(String &string1,String &string2){if(strcmp(string1.p,string2.p)>0){return true;}elsereturn false;}bool operator<(String &string1,String &string2){if(strcmp(string1.p,string2.p)<0){return true;}elsereturn false;}bool operator==(String &string1,String &string2){if(strcmp(string1.p,string2.p)==0){return true;}elsereturn false;}void compare(String &string1,String &string2){if(operator >(string1,string2)==1){string1.display();cout<<">";string2.display();}else if(operator <(string1,string2)==1){string1.display();cout<<"<";string2.display();}else if(operator ==(string1,string2)==1){string1.display();cout<<"==";string2.display();}cout<<endl;}int main(){String string1("Hello"),string2("Book"),string3("computer"),string4("Hello");compare(string1,string2);compare(string2,string3);compare(string1,string4);return 0;

ubuntu@ubuntu:~$ g++ 13.cpp -o a13.cpp: In function ‘int main()’:13.cpp:79:24: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]  String string1("Hello"),string2("Book"),string3("computer"),string4("Hello");                        ^13.cpp:79:40: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]  String string1("Hello"),string2("Book"),string3("computer"),string4("Hello");                                        ^13.cpp:79:60: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]  String string1("Hello"),string2("Book"),string3("computer"),string4("Hello");                                                            ^13.cpp:79:77: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]  String string1("Hello"),string2("Book"),string3("computer"),string4("Hello");                                                                             ^ubuntu@ubuntu:~$ ./aHello>BookBook<computerHello==Hello

要注意这个程序中，需用到头文件#include <cstring>,有关这个头文件的使用，目前我也不是太清楚！对于运行的警告信息，暂时无法作出解释！

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