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Merge pull request #75 from techkang/patch-2

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Update 重要.cpp
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Francis 2020-10-17 08:56:06 +08:00 committed by GitHub
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practical_exercises/10_day_practice/day7/综合例题/重要.cpp
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@ -1,66 +1,87 @@
//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 <iostream>
#include <cstring> #include <cstring>
using namespace std; using namespace std;
class String { class String
{
private: private:
int length; //字符串长度 int length; //字符串长度
char *sPtr; //存放字符串的指针 char *sPtr; //存放字符串的指针
void setString( const char *s2); void setString(const char *s2);
friend ostream &operator<<(ostream &os, const String &s); friend ostream &operator<<(ostream &os, const String &s)
friend istream &operator>>(istream &is, String &s); //重载输入运算符 {
return os << s.sPtr;
};
friend istream &operator>>(istream &is, String &s)
{
return is >> s.sPtr;
}; //重载输入运算符
public: public:
String( const char * = "" ); String(const char * = "");
const String &operator=(const String &R); //重载赋值运算符 = const String &operator=(const String &R)
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 == length = R.length;
bool operator!=(const String &R); //字符串的不等比较 != strcpy(R.sPtr, sPtr);
bool operator!() ; //判定字符串是否为空 return *this;
bool operator<(const String &R) const; //字符串的小于比较 < }; //重载赋值运算符 =
bool operator>(const String &R); //字符串的大于比较 > const String &operator+=(const String &R); //字符串的连接 +=
bool operator>=(const String &R); //字符串的大于等于比较 bool operator==(const String &R); //字符串的相等比较 ==
char &operator[](int); //字符串的下标运算 bool operator!=(const String &R); //字符串的不等比较 !=
~String(); 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) { const String &String::operator+=(const String &R)
{
char *temp = sPtr; char *temp = sPtr;
length += R.length; length += R.length;
sPtr = new char[length+1]; sPtr = new char[length + 1];
strcpy(sPtr,temp ); strcpy(sPtr, temp);
strcat(sPtr,R.sPtr ); strcat(sPtr, R.sPtr);
delete [] temp; delete[] temp;
return *this; return *this;
} }
bool String::operator==(const String &R){return strcmp(sPtr,R.sPtr)==0;} String::String(const char *str)
bool String::operator!=(const String & R){return !(*this==R);} {
bool String::operator!(){return length ==0;} sPtr = new char[strlen(str) + 1];
bool String::operator<(const String &R)const{return strcmp(sPtr,R.sPtr)<0;} strcpy(sPtr, str);
bool String::operator>(const String &R){return R<*this;} length = strlen(str);
bool String::operator>=(const String &R){return !(*this<R);} };
char &String::operator[](int subscript){return sPtr[subscript];} bool String::operator==(const String &R) { return strcmp(sPtr, R.sPtr) == 0; }
int main(){ bool String::operator!=(const String &R) { return !(*this == R); }
String s1("happy"),s2("new year"),s3; 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 cout << "s1 is " << s1 << "\ns2 is " << s2 << "\ns3 is " << s3
<< "\n比较s2和s1:" << "\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") << "\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: "; cout << "\n\n测试s3是否为空: ";
if (!s3){ if (!s3)
cout << "s3是空串"<<endl; //L3 {
cout<<"把s1赋给s3的结果是："; cout << "s3是空串" << endl; //L3
cout << "把s1赋给s3的结果是：";
s3 = s1; s3 = s1;
cout << "s3=" << s3 << "\n"; //L5 cout << "s3=" << s3 << "\n"; //L5
} }
cout << "s1 += s2 的结果是：s1="; //L6 cout << "s1 += s2 的结果是：s1="; //L6
s1 += s2; s1 += s2;
cout << s1; //L7 cout << s1; //L7
cout << "\ns1 += to you 的结果是："; //L8 cout << "\ns1 += to you 的结果是："; //L8
s1 += " to you"; s1 += " to you";
cout << "s1 = " << s1 <<endl; //L9 cout << "s1 = " << s1 << endl; //L9
s1[0] = 'H'; s1[0] = 'H';
s1[6] = 'N'; s1[6] = 'N';
s1[10] = 'Y'; s1[10] = 'Y';