C++基础入门4——程序流程结构

int main()
{
	//打印10*10正方形点阵
	for (int i = 0; i < 10; i++)
	{
		for (int i = 0; i < 10; i++)
		{
			cout << "*";
		}
		cout << endl;
	}
	return 0;
}

 

1. 选择结构

1）if语句

 实例：

//多条if语句形式
int main()
{
	int pig1 = 0;
	int pig2 = 0;
	int pig3 = 0;
	int max = 0;
	cout << "请输入三只小猪的体重："  << endl;
	cout << "pig1：" << endl;
	cin >> pig1;
	cout << "pig2：" << endl;
	cin >> pig2;
	cout << "pig3：" << endl;
	cin >> pig3;
	if (pig1 >= pig2 && pig1 >= pig3)
	{
		cout << "体重最重的小猪是小猪1"  << endl;
	}
	else if (pig1 >= pig2 && pig1<= pig3)
	{
		cout << "体重最重的小猪是小猪3" << endl;
	}
	else if (pig1 <= pig2 && pig2 <= pig3)
	{
		cout << "体重最重的小猪是小猪3" << endl;
	}
	else if (pig1 <= pig2 && pig2 >= pig3)
	{
		cout << "体重最重的小猪是小猪2" << endl;
	}
	return 0;
}

//嵌套if语句形式
int main()
{
	int pig1 = 0;
	int pig2 = 0;
	int pig3 = 0;
	int max = 0;
	cout << "请输入三只小猪的体重："  << endl;
	cout << "pig1：" << endl;
	cin >> pig1;
	cout << "pig2：" << endl;
	cin >> pig2;
	cout << "pig3：" << endl;
	cin >> pig3;
	if (pig1 > pig2)
	{
		if (pig1 > pig3)
		{
			cout << "小猪1最重" << endl;
		}
		else
		{
			cout << "小猪3最重" << endl;
		}
	}
	else
	{
		if (pig2 > pig3)
		{
			cout << "小猪2最重" << endl;
		}
		else
		{
			cout << "小猪3最重" << endl;
		}
	}
	return 0;
}

2）三目运算符

3）switch语句 

 

//switch语句只能判断整型或者字符型，不能对区间进行判定
int main()
{
	int score = 0;
	cout << "请输入您的评分：" << endl;
	cin >> score;
	switch (score)
	{
	case 5: 
		cout << "您对电影的评级为优秀" << endl;
		break;
	case 4:
		cout << "您对电影的评级为良好" << endl;
		break;
	case 3:
		cout << "您对电影的评级为不错" << endl;
		break;
	case 2:
		cout << "您对电影的评级为还行" << endl;
		break;
	case 1:
		cout << "您对电影的评级为烂片" << endl;
		break;
	}
	return 0;
}

2. 循环结构

1）while循环语句

 

int main()
{
	int RandNumber = rand() %% 100 + 1;//生成一个1到100之间的随机数
	cout << "系统给出的随机数字是：" << RandNumber << endl;
	int GuessNumber = 0;
	cout << "请输入您猜想的数字：" << endl;
	cin >> GuessNumber;
	while (GuessNumber != RandNumber)
	{
		if (GuessNumber > RandNumber)
		{
			cout << "抱歉，您猜测的数字过大。请继续！" << endl;
			cout << "请输入您猜想的数字：" << endl;
		}
		else
		{
			cout << "抱歉，您猜测的数字过小。请继续！" << endl;
			cout << "请输入您猜想的数字：" << endl;
		}
		cin >> GuessNumber;
	}
	cout << "恭喜，您猜对了。" << endl;
	return 0;
}

2）do...while循环语句

int main()
{
	//输出0-9之间的数字
	int num = 0;
	do
	{
		cout << num << endl;
		num++;
	} while (num < 10);
	return 0;
}

 

int main()
{
	//输出所有的水仙花数
	int num = 100;
	int num100 = 0;
	int num10 = 0;
	int num1 = 0;
	do
	{
		num100 = num / 100;
		num10 = (num - num100*100)/10;
		num1 = num %% 10;
		if (num == pow(num100,3) + pow(num10, 3) + pow(num1, 3))
		{
			cout << num << endl;
		}
		num++;
	} while (num < 1000);
	return 0;
}

 

3）for循环语句

 

 

int main()
{
	//敲桌子问题
	for (int num = 1; num <= 100; num++)
	{
		if (num %% 10 == 7)
		{
			cout << "敲桌子" << endl;
		}
		else if (num / 10 == 7)
		{
			cout << "敲桌子" << endl;
		}
		else if (num %% 7 == 0)
		{
			cout << "敲桌子" << endl;
		}
		else
		{
			cout << num << endl;
		}
	}
	return 0;
}

4）嵌套循环

 

 

 

int main()
{
	//打印九九乘法口诀表
	for (int i = 1; i < 10; i++)
	{
		for (int j = 1; j <= i; j++)
		{
			cout << j << "x" << i << "=" << i * j << " ";
		}
		cout << endl;
	}
	return 0;
}

 

3. 跳转语句

1）break语句

 2）continue语句

在循环语句中，跳过本次循环中余下尚未执行的语句，继续执行下一次循环

 

 

3）goto语句