4.7 4.9 节练习

练习 4.21

#include <iostream>  
#include <string>
#include <vector>
using namespace std;


int main()
{	
	vector<int> pool;
	int i;
	while (cin >> i)
		pool.push_back(i);
	for (auto &a : pool)
	{
		a = (a % 2 == 0) ?  a : 2*a;
		cout << a << " ";
	}
	cout << endl;
	system("pause");
	return 0;
}

练习4.22

#include <iostream>  
#include <string>
#include <vector>
using namespace std;


int main()
{	
	/*比较运算符*/
	int grade = 0;
	while(cin >> grade)
	cout << ((grade > 90) ? "high pass" : (grade > 75) ? " pass" : (grade > 60) ? "low pass" : "fail")<<endl;
	system("pause");
	return 0;
}

练习4.28

#include <iostream>  
#include <string>
#include <vector>
using namespace std;


int main()
{	
	cout << "类型名称\t" << "所占字节数" << endl;
	cout << "int\t\t" << sizeof(int) << endl;
	cout << "char\t\t" << sizeof(char) << endl;
	cout << "unsigned int\t" << sizeof(unsigned int) << endl;
	cout << "wchar_t\t\t" << sizeof(wchar_t) << endl;
	cout << "char16_t\t" << sizeof(char16_t) << endl;
	cout << "char32_t\t" << sizeof(char32_t) << endl;
	cout << "short\t\t" << sizeof(short) << endl;
	cout << "long\t\t" << sizeof(long) << endl;
	cout << "long long\t" << sizeof(long long) << endl;
	cout << "float\t\t" << sizeof(float) << endl;
	cout << "double\t\t" << sizeof(double) << endl;
	cout << "long double\t" << sizeof(long double) << endl;
	cout << "bool\t\t" << sizeof(bool) << endl;
	system("pause");
	return 0;
}

可以看到各种内置类型所占字节数。