习题6.4 逻辑或运算符OR ||

#include<iostream>
int main()
{
using namespace std;
cout << "阿稳是个帅哥吗？"; char ch; cin >> ch;
if (ch == 'y' || ch == 'Y')
cout << "你说得对，阿稳是个帅哥！";
else if (ch == 'n' || ch == 'N')
cout << "你说的不对，阿稳应该是个大帅哥！";
else
cout << "你说得很对！";
return 0;
}

习题6.5 逻辑与运算符AND &&

由于两种不同原因而结束的while循环，一个while循环将值读入到数组，一个测试（i<ArSize）在数组被填满时循环结束，另一个测试（temp >= 0）让用户通过输入一个负值来提前结束循环。

#include<iostream>
const int Arsize = 6;
int main()
{
using namespace std;
float naaq[Arsize];
cout << "Enter the NAAQs:\n";
int i = 0;

float temp; 

cout << "First value: "; 

cin >> temp;
while (i < Arsize && temp >= 0)
{
naaq[i] = temp;
++i;
if (i < Arsize) 

{ cout << "Next value: "; 

cin >> temp;
}
}
if (i == 0)
cout << "No date -- bye\n"; 

else

{ cout << "Enter your NAAQ: "; 

float you; 

cin >> you;
int count = 0;
for (int j = 0; j < i; j++) 

{ if (naaq[j] > you)
++count;
}
cout << count;
}
return 0;
}

课后习题

课堂巧思

设计一个有限单个密码锁，密码为提前设定好的单个字符，用户可以输入字符，如果输错密码，提示密码错误，还有几次机会；密码错误三次则提示“no more chances”然后退出，密码正确提示”welcome”然后退出。

桂桂答题

#include<iostream>
const char code = 'c';
int main()
{
	using namespace std;
	char ch;
	int chances = 3;
	cout << "Pls enter your code.\n";
	cin >> ch;
	while (ch != code)
	{
		chances = chances - 1;
		if (chances == 0)
		{
			cout << "Wrong, there is no chance left. Bye!\n";
			return 0;
		}
		else
		{
			cout << "Wrong, there is/are " << chances << " chances left for you!\n";
			cin >> ch;
		}
	}
	cout << "welcome!\n";
	return 0;
}

课后延伸

设计一个三位密码锁，密码为提前设定好的字符串，用户可以输入字符，如果输错密码，提示密码错误，输对密码则提示:”welcome“。

桂桂答题

#include<iostream>
const char code[4] = "wsg";
int main()
{
	using namespace std;
	char ch[4];
	int i = 0;
	cin >> ch[i];
	while (i < 2)
	{
		if (ch[i] != code[i])
		{
			cout << "wrong\n";
			break;
		}
		else
			i++;
		cin >> ch[i];
	}
	if (ch[i] == code[i])
		cout << "welcome\n";
	else
		cout << "Bye\n";
}

试着这样做：如果输错任意一位密码，立马提示密码错误退出

100分

课后习题答案

	int count = 0;
	char ch;
	cout << "pls guess the code:";
	while (count != 3)
	{
		cin >> ch;
		if (ch == Code)
		{
			cout << "welcome\n";
			return 0;
		}
		else
		{
			count++;
			cout << "code wrong! " << 3 - count << " chances left\n";
			
		}
	}
	cout << "no more chances";

//答案2
#include<iostream>
int main()
{
	using namespace std;
	const char code = 'g';
	int chances = 3;
	char ch;
	cout << "pls enter the code:";
	cin >> ch;
	while (ch != code && chances != 0)
	{
		chances--;
		cout << "wrong! " << chances << "chances left!\n";
		cin >> ch;
	}
	if (chances == 0)
		cout << "no chances left!\n";
	else
		cout << "welcome";


}

	using namespace std;
	const char code[4] = "wsg";
	char guess[4];
	int i = 0;
	int count = 0;
	cout << "pls enter the code: ";
	cin >> guess[i];
	while (i < 2 && guess[i]==code[i])
	{
		i++;
		cin >> guess[i];
	}
	if (i != 2 || guess[i] != code[i])
	{
		cout << "wrong!";
	}
	else
		cout << "welcome!";


	return 0;

桂桂评分：F→SSSS