作业1：实现类中有类的几个特殊成员函数
#include <iostream>
using namespace std;
class Person
{
string name;
int *age;
public:
Person():name("none"),age(new int(0)){}
Person(int age):age(new int(age)){}
Person(string name,int age):name(name),age(new int(age)){}
Person(const Person &other):name(other.name),age(new int(*(other.age))){}
~Person()
{
delete age;
}
void show();
void set_age(int age)
{
*(this->age) = age;
}
Person &operator=(const Person &other)
{
name = other.name;
*age = *(other.age);
return *this;
}
};
class Stu
{
Person p1;
const double score;
public:
Stu(string name,int age,double score):p1(name,age),score(score){}
Stu():score(0){}
Stu(const Stu &other):p1(other.p1),score(other.score){}
~Stu(){ }
void show();
void set_age(int age)
{
p1.set_age(age);
}
Stu &operator=(const Stu &other)
{
p1.operator=(other.p1);
return *this;
}
};
void Person::show()
{
cout << "name: " << name << endl;
cout << "age: " << *age << endl;
}
void Stu::show()
{
p1.show();
cout << "score: " << score << endl;
}
int main()
{
Stu *s1 = new Stu;
s1->show();
delete s1;
cout << endl;
Stu *s2 = new Stu ("张三",18,99.8);
s2->show();
delete s2;
cout << endl;
Stu s3("李四",25,25.5);
s3.show();
cout << endl;
Stu s4 = s3;
s4.show();
cout << endl;
s3.set_age(99);
s3.show();
cout << endl;
s4.show();
cout << endl;
s4.operator=(s3);
s4.show();
return 0;
}
作业2：实现自定义Mystring
#include <iostream>
#include <cstring>
using namespace std;
char c = '\0';
class My_string
{
char *str; //记录C风格的字符串
int size; //记录字符串长度
public:
//无参构造
//有参构造
//拷贝构造
//拷贝赋值
//析构函数
//at函数
char &my_at(int num);
};答案1（优化版）：
#include <iostream>
#include <cstring>
using namespace std;
class Mystring
{
char *str;
int len;
public:
// 无参构造函数
Mystring() : str(new char[1]), len(0)
{
str[0] = '\0'; // 确保空字符串以null结尾
}
// 有参构造函数
Mystring(const char *str)
{
len = strlen(str);
this->str = new char[len + 1]; // +1 为结束符留空间
strcpy(this->str, str);
}
~Mystring()
{
delete [] str;
}
//拷贝构造函数
Mystring(const Mystring &other)
{
this->len = other.len;
this->str = new char[other.len+1];
strcpy(this->str,other.str);
}
// 拷贝赋值函数
Mystring &operator=(const Mystring &other)
{
if (this != &other)
{ // 添加自赋值检查
delete[] str; // 先删除原有内存
len = other.len;
str = new char[len + 1]; // +1 为结束符留空间
strcpy(str, other.str);
}
return *this;
}
// 加法运算符重载
Mystring operator+(const Mystring &other) const // 返回新对象，参数使用const
{
Mystring result;
result.len = this->len + other.len;
delete[] result.str; // 删除默认构造函数分配的内存
result.str = new char[result.len + 1]; // +1 为结束符留空间
strcpy(result.str, this->str);
strcat(result.str, other.str);
return result;
}
char &my_at(int location)
{
if(location>len)
{
perror("越界访问");
}
return *(str+location-1);
}
void show()
{
printf(str);
}
};
int main()
{
char s[10] = "hello";
Mystring str1(s);
str1.show();
cout << endl;
Mystring str2("world");
str2.show();
cout << endl;
Mystring str3 = str2; // 复制构造
str3.show();
cout << endl;
Mystring str4;
str4 = str1 + str2; // 使用加法运算符
str4.show();
cout << endl;
cout << str4.my_at(16) << endl;
return 0;
}
答案2：
#include <iostream>
#include <cstring>
using namespace std;
class Mystring
{
char *str;
int len;
public:
Mystring():str(new char[4]{0}),len(4){}
Mystring(const char *str)
{
this->len = strlen(str);
this->str = new char[len];
for(int i=0;i<len;i++)
{
*((this->str)+i) = *(str+i);
}
}
~Mystring()
{
delete [] str;
}
Mystring(const Mystring &other)
{
this->len = other.len;
this->str = new char[this->len];
for(int i=0;i<len;i++)
{
*((this->str)+i) = *((other.str)+i);
}
}
// 修改赋值运算符
Mystring &operator=(const Mystring &other)
{
if(this != &other) // 添加自赋值检查
{
char *temp = new char[other.len]; // 先分配新内存
for(int i = 0; i < other.len; i++)
{
temp[i] = other.str[i];
}
delete[] str; // 再删除旧内存
str = temp;
len = other.len;
}
return *this;
}
Mystring operator+(Mystring &other)
{
Mystring temp;
delete[] temp.str; // 释放默认构造的内存
temp.len = this->len+other.len;
temp.str = new char [temp.len];
for(int i = 0;i<temp.len;i++)
{
if(i<this->len)
{
*((temp.str)+i) = *((this->str)+i);
}
else
{
*((temp.str)+i) = *((other.str+i)-this->len);
}
}
return temp;
}
void show()
{
for(int i = 0;i<len;i++)
{
printf("%c",*((this->str)+i));
}
}
};
int main()
{
char s[10] = "hello";
Mystring str1(s);
str1.show();
cout << endl;
Mystring str2("world");
str2.show();
cout << endl;
Mystring str3 = str2;
str3.show();
cout << endl;
Mystring str4;
str4 = str1+str2;
str4.show();
cout << endl;
return 0;
}