Accelerated C++学习笔记 chapter 2

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最新推荐文章于 2025-09-08 21:29:33 发布

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分类专栏： Accelerated C ++学习笔记文章标签： c ++ 字符串的使用 c++ string

本文链接：https://blog.youkuaiyun.com/jiangjieqazwsx/article/details/44025071

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本文通过几个具体的C++程序实例，介绍了如何实现用户输入姓名后的个性化问候、不同形状的字符输出、倒序输出整数等实用功能。

2.0、请求某人输入其姓名，然后向这个人发出问候

#include <iostream>
#include <string>

using namespace std;

int main()
{
	//请求用户输入姓名
	cout << "please enter your first name: ";

	//读入用户输入的姓名
	string name;
	cin >> name;

	//构造我们将要输出的信息
	const string greeting = "hello, " + name + "!";
	
	//围住问候语的空白个数
	const int pad = 1;
	
	//待输出的行数与列数
	const int rows = 2 * pad + 3;
	const string::size_type cols = greeting.size() + 2 * pad + 2;
	
	//输出一个空白行，将输出和输入分隔开
	cout << endl;

	//输出row行
	//不变式：到目前为止，我们已经输出了r行
	for (int r = 0; r < rows; r ++)
	{
		string::size_type c = 0;
		//不变式：到目前为止，我们已经输出了c 个字符
		while(c != cols)
		{
			//是否应该输出问候语了？
			if (r == pad + 1 && c == pad + 1)
			{
				cout << greeting;
				c += greeting.size();
			}else{
				//我们是否位为边界上
				if (r == 0 || r == rows - 1 || c == 0 || c == cols - 1)
					cout << "*";
				else
					cout << ' ';
				c ++;
			}
		}
		cout << endl;
	}
	return 0;
}

运行结果

2.1改成框架没有间隔的问候语

#include <iostream>
#include <string>

using namespace std;

int main()
{
	cout << "please enter your first name: ";

	string name;
	cin >> name;

	const string greeting = "hello, " + name + "!";
	const int rows =3;
	const string::size_type cols = greeting.size()+ 2;
	cout << endl;

	for (int r = 0; r < rows; r ++)
	{
		string::size_type c = 0;
		while(c != cols)
		{
			if (r == 1 && c ==1)
			{
				cout << greeting;
				c += greeting.size();
			}else{
					cout << "*";
					c ++;
			}
		}
		cout << endl;
	}
	return 0;
}

运行结果

2.3重写框架，让用户自己提供在框架和问候语间的空格个数

#include <iostream>
#include <string>

using namespace std;

int main()
{
	cout << "please enter your first name: ";

	string name;
	cin >> name;
	
	//用户提供空格个数
	cout << endl << "please enter the number of pad you want: ";
	int pad;
	cin >> pad;	

	const string greeting = "hello, " + name + "!";
	const int rows = 2 * pad + 3;
	const string::size_type cols = greeting.size() + 2 * pad + 2;
	cout << endl;

	for (int r = 0; r < rows; r ++)
	{
		string::size_type c = 0;
		while(c != cols)
		{
			if (r == pad + 1 && c == pad + 1)
			{
				cout << greeting;
				c += greeting.size();
			}else{
				if (r == 0 || r == rows - 1 || c == 0 || c == cols - 1)
					cout << "*";
				else
					cout << ' ';
				c ++;
			}
		}
		cout << endl;
	}
	return 0;
}

运行结果：

2.5编写一个程序，让它输出一系列的"*"字符，程序输出的这些字符将构成一个正方形，一个长方形，一个三角形

#include <iostream>
#include <string>

using namespace std;

int main()
{
	cout << "**" << endl;
	cout << "**" << endl;
	cout << endl;

	cout << "***" << endl;
	cout << "***" << endl;
	cout << endl;

	cout << "*" << endl;
	cout << "**" << endl;
	return 0;
}

运行结果：

2.7编写一个程序来依次输出从10~-5的整数

#include <iostream>
#include <string>

using namespace std;

int main()
{
	int i = 10;
	while( i >= -5){
		cout << i << endl;
		i -= 1;
	}
	return 0;
}

运行结果：

2.8编写一个程序来计算区间[1.10）中的所有数值的乘积。

#include <iostream>
#include <string>

using namespace std;

int main()
{
	int sum = 1;
	for(int i = 1; i < 10; i ++)
	{
		sum *= i;
	}
	cout << "sum = " <<sum;
	return 0;
}

运行结果：

2.9编写一个程序，让用户输入两个数值并告知用户在这两个数值中哪一个较大

<pre name="code" class="cpp">#include <iostream>
#include <string>

using namespace std;

int main()
{
	int a, b;
	cout << "please input two fingers: ";
	cin >> a >> b;
	if (a >= b)
		cout << "the first number is bigger" << endl;
	else
		cout << "the second number is bigger" << endl;
}

运行结果：

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