利用嵌套打印十行 *

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#include<iostream>
using namespace std;

int main() 
{
	//利用嵌套打印十行*
	for (int j = 0; j <= 5; j++)
	{
		for (int i = 0; i <= 10; i++)
		{
			cout << "*";
			
		}
		cout << endl;
	}
	return 0;
}

利用嵌套打印乘法口诀表

首先打印行

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#include<iostream>
using namespace std;

int main()
{
	for (int i = 1; i <= 9; i++)
	{
		cout << "i" << endl;
	}
	system("pause");
	return 0;
}

运行此代码发现打印的是九行i

image-20220111001728129

原因是i加了 “”

将 “” 去掉

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#include<iostream>
using namespace std;

int main()
{
	for (int i = 1; i <= 9; i++)
	{
		cout << i << endl;
	}
	system("pause");
	return 0;
}

嵌套for循环拆解

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#include<iostream>
using namespace std;

int main()
{
	for (int i = 1; i <= 9; i++)
	{
		cout << i << endl;
		for (int j = 1; j <= i; j++)
		{
			cout << j;
		}
		
	}
	system("pause");
	return 0;
}

拆解后

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#include<iostream>
using namespace std;

int main()
{
	int i = 1;
	for (; ; )
	{
		if (i > 9)
		{
			break;
		}
		cout << i << endl;
		
		int j = 1;
		for (; ; )
		{
			if (j > i)
			{
				break;
			}
			cout << j;
			j++;

		}
		i++;
	}
	system("pause");
	return 0;
}

打印列数

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#include<iostream>
using namespace std;

int main()
{
	for (int i = 1; i <= 9; i++)
	{
		
		for (int j = 1; j <= i; j++)
		{
			cout << "j*i"<<"="<<"\t";
			
		}
		cout << endl;
	}
	system("pause");
	return 0;
}

发现打印完后是这样的结果

image-20220111130021215

改正如下

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#include<iostream>
using namespace std;

int main()
{
	for (int i = 1; i <= 9; i++)
	{
		
		for (int j = 1; j <= i; j++)
		{
			cout << j << "*" << i << "=" << j * i << "\t";
		}
		cout << endl;
	}
	system("pause");
	return 0;
}