c++基础篇4（条件判断语句）

1.判断输入数是否为奇数

#include
using namespace std;
void main()
{
	int input;
	cout << "请输入整数" << endl;
	cin >> input;
	if (input % 2 != 0)
	{
		cout << "输入为奇数" << endl;
	}
	system("pause");
}

结果：

2.根据分数判断是否优秀

#include
using namespace std;
void main()
{
	int input;
	cout << "请输入分数" << endl;
	cin >> input;
	if (input > 90)
	{
		cout << "优秀" << endl;
	}
	else
	{
		cout << "需要努力了" << endl;
	}
	system("pause");
}

结果：

3改进奇偶性判别

#include
using namespace std;
void main()
{
	int input;
	cout << "请输入数值" << endl;
	cin >> input;
	if (input%2==0)
	{
		cout << "偶数" << endl;
	}
	else
	{
		cout << "奇数" << endl;
	}
	system("pause");
}

结果：

4.根据成绩划分等级

#include
using namespace std;
void main()
{
	int input;
	cout << "请输入数值" << endl;
	cin >> input;
	if (input>=90)
	{
		cout << "优秀" << endl;
	}
	else if(input>=60&&input<90)
	{
		cout << "合格" << endl;
	}
	else
	{
		cout << "需要努力了" << endl;
	}
	system("pause");
}

结果：

5.用条件运算符完成判断数奇偶性

#include
using namespace std;
void main()
{
	int input;
	cout << "输入数值" << endl;
	cin >> input;
	(input % 2 == 0) ? (cout << "偶数" << endl) : (cout << "奇数" << endl);
	system("pause");
}

结果:

6.用条件表达式判断一个数是否为3和5的整倍数

#include
using namespace std;
void main()
{
	int input;
	cout << "输入数值" << endl;
	cin >> input;
	(input % 3== 0&& input % 5==0) ? (cout << "是" << endl) : (cout << "否" << endl);
	system("pause");
}

结果：

7用条件表达式判断一个数是否为3和5的整倍数（嵌套）

#include
using namespace std;
void main()
{
	int input;
	cout << "输入数值" << endl;
	cin >> input;
	(input % 3 == 0) ?
	 		((input % 5 == 0) ? cout << "是" << endl : cout << "否" << endl)
			 :cout << "否" << endl;
	system("pause");
}

结果：

8.根据输入的字符输出字符串

#include
using namespace std;
void main()
{
	char input;
	cout << "输入数值" << endl;
	cin >> input;
	switch (input)
	{
	case 'a':
			cout<< "very good" << endl;
			break;
	case 'b':
			cout << "good" << endl;
			break;
	case 'c':
			cout << "normal" << endl;
			break;
	case 'd':
			cout << "failure" << endl;
			break;
	default:
		cout << "input error" << endl;
	}
	system("pause");
}

结果：

9根据输入的字符输出字符串

#include
using namespace std;
void main()
{
	char input;
	cout << "输入字符" << endl;
	cin >> input;
	if (input == 'a')
	{
		cout << "very good" << endl;
		system("pause");
		return;               //return是跳出主函数，所以每一条之前加一个system	
	}
	if (input == 'b')
	{
		cout << "good" << endl;
		system("pause");
		return;
	}
	if (input == 'c')
	{
		cout << "normal" << endl;
		system("pause");
		return;	
	}
	if (input == 'd')
	{
		cout << "failure" << endl;
		system("pause");
		return;
	}
	cout << "input error" << endl;
	system("pause");
}

结果：

10.根据输入的字符输出字符串

#include
using namespace std;
void main()
{
	char input;
	cout << "输入字符" << endl;
	cin >> input;
	if (input == 'a')
	{
		cout << "very good" << endl;
		system("pause");
		return;               //return是跳出主函数，所以每一条之前加一个system	
	}
	else if (input == 'b')
	{
		cout << "good" << endl;
		system("pause");
		return;
	}
	else if (input == 'c')
	{
		cout << "normal" << endl;
		system("pause");
		return;	
	}
	else if (input == 'd')
	{
		cout << "failure" << endl;
		system("pause");
		return;
	}
	else
	{
		cout << "input error" << endl;
		system("pause");
	}
}

结果：

#include
using namespace std;
void main()
{
	int input;
	cout << "输入" << endl;
	cin >> input;
	switch(input)                 //没有break，会顺序执行完。
	{
	case 1:
		cout << "Monday" << endl;
	case 2:
		cout << "Tuesday" << endl;
	case 3:
		cout << "Wednesday" << endl;
	case 4:
		cout << "Thursday" << endl;
	case 5:
		cout << "Friday" << endl;
	case 6:
		cout << "Saturday" << endl;
	case 7:
		cout << "Sunday" << endl;
	default:
		cout << "input error" << endl;
	}
	
	system("pause");
	
}

结果:

12.判断语句的嵌套（判断是否为闰年）

#include
using namespace std;
void main()
{
	int year;
	cin >> year;
	if (year % 4 == 0)
	{
		if (year % 400 == 0)
		{
			cout << "是" << endl;
		}
		else
			cout << "不是" << endl;
	}
	else
		cout << "不是" << endl;
	system("pause");
	
}

结果：

12.判断是否为闰年

#include
using namespace std;
void main()
{
	int year;
	cin >> year;
	if (year%4 == 0&&year%400==0)
	{
		cout << "是" << endl;
	}
	else
		cout << "不是" << endl;
	system("pause");
	
}

结果：

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