**疫情期间学习C++
4-1
需要使用cin.get()设置读取位数，避免空格导致无法读取多个词

#include <iostream>
struct info_people //define structure
{char first_name[20];char last_name[20];char grade;unsigned int age;
};
int main()
{using namespace std;info_people* pd = new info_people;cout << "What is your first name?";cin.get(pd->first_name, 20);cout << endl << "What is your last name?";cin >> (*pd).last_name;cout << endl << "What letter grade do you deserve?";cin >> (*pd).grade;cout << endl << "What is your age?";cin >> pd->age;cout << endl << "Name: " << (*pd).first_name << ", " << (*pd).last_name << endl;cout << "Grade: " << char((*pd).grade + 1) << endl;cout << "Age: " << (*pd).age << endl;delete pd;return 0;
}

4-2
getline(cin,name)用于读取一行的string

#include <iostream>
#include <string>
int main()
{using namespace std;string name;string dessert;cout << "Enter your name:\n";getline(cin, name);cout << "Enter your favourite dessert:\n";getline(cin, dessert);cout << "I have some delicious " << dessert;cout << " for you, " << name << ".\n";return 0;
}

4-3
char设置长度，没空格可以直接cin

#include <iostream>
#include <cstring>
int main()
{using namespace std;const int size = 15;char first_name[size];char last_name[size];string dessert;cout << "Enter your fisrt name: ";cin >> first_name;cout << "\nEnter your last name: ";cin >> last_name;cout << "\nHere's the information in a single string: " << first_name << ", " << last_name << endl;return 0;
}

4-4
不含空格同样可以直接cin

#include <iostream>
#include <string>
int main()
{using namespace std;string first_name;string last_name;string dessert;cout << "Enter your fisrt name: ";cin >> first_name;cout << "\nEnter your last name: ";cin >> last_name;cout << "\nHere's the information in a single string: " << first_name << ", " << last_name << endl;return 0;
}

4-5

#include <iostream>
struct CandyBar
{char brand[20];float weight;unsigned int cal;
};int main()
{using namespace std;CandyBar snack ={"Mocha Munch", 2.3, 350};cout << "Brand: " << snack.brand << "\nWeight: " << snack.weight << "\nCal: " << snack.cal << endl;return 0;
}

4-6
不知道题目的意思理解错了没有。。。

#include <iostream>
struct CandyBar
{char brand[20];float weight;unsigned int cal;
};int main()
{using namespace std;CandyBar snack;cout << "Enter the brand: ";cin >> snack.brand;cout << "\nEnter the weight: ";cin >> snack.weight;cout << "\nEnter the cal: ";cin >> snack.cal;cout << "Brand: " << snack.brand << "\nWeight: " << snack.weight << "\nCal: " << snack.cal << endl;return 0;
}

4-7

#include <iostream>
#include <string>
struct Pissa_Info
{std::string brand;float diameter;float weight;
};int main()
{using namespace std;Pissa_Info pissa;cout << "Enter the brand: ";getline(cin, pissa.brand);cout << endl << "Enter the diameter: ";cin >> pissa.diameter;cout << endl << "Enter the weight: ";cin >> pissa.weight;cout << "Brand: " << pissa.brand << "\nDiameter: " << pissa.diameter << "\nWeight: " << pissa.weight<< endl;return 0;
}

4-8
cin数字之后，要使用getline的话需要先用cin.get(）跳过换行符

#include <iostream>
#include <string>
using namespace std;struct Pissa_Info
{string brand;float diameter;float weight;
};int main()
{Pissa_Info* pd = new Pissa_Info;cout << "Enter the diameter: ";cin >> pd->diameter;cin.get();cout << endl << "Enter the brand: ";getline(cin, pd->brand);cout << endl << "Enter the weight: ";cin >> pd->weight;cout << "Brand: " << (*pd).brand << "\nDiameter: " << (*pd).diameter << "\nWeight: " << (*pd).weight<< endl;delete pd;return 0;
}

4-9

#include <iostream>
#include <string>
using namespace std;
struct CandyBar
{string brand;float weight;unsigned int cal;
};int main()
{CandyBar* pd = new CandyBar;cout << "Enter the brand: ";getline(cin, pd->brand);cout << "\nEnter the weight: ";cin >> pd->weight;cout << "\nEnter the cal: ";cin >> pd->cal;cout << "Brand: " << (*pd).brand << "\nWeight: " << (*pd).weight << "\nCal: " << (*pd).cal << endl;delete pd;return 0;
}

4-10

#include
#include

int main()
{
using namespace std;
array<float, 3> grade;
cout << "The first time finish 40m: ";
cin >> grade[0];
cout << "\nThe second time finish 40m: ";
cin >> grade[1];
cout << "\nThe third time finish 40m: ";
cin >> grade[2];
cout << "Average time is " << (grade[0] + grade[1] + grade[2]) / 3 << endl;
return 0;
}