面试训练顺时针打印矩阵

题目：输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字。

例如：如果输入如下矩阵：

1 2 3 4

5 6 7 8

9 10 11 12

13 14 15 16

则依次打印出数字1, 2, 3, 4, 8, 12, 16, 15, 14, 13, 9, 5, 6, 7, 11, 10。

今天中午没有睡午觉，头晕的啊不行。看海涛的递归看了好久没反应，自己思路和他的基本一致，主要的问题就是 边界条件的处理上面有问题。头昏所以先放放。

看到下面一个网友的评论中，采用四个边界来固定遍历，即左边界，右边界，上边界，下边界，无外乎就在这四个边界中移动，如果出现边界重合即退出。

#include "stdio.h"

int main()
{
	int upbound,downbound,leftbound,rightbound;
	int data[3][3] ={
					{1,2,3},
					{5,6,7},
					{8,9,10},
	};
	int row,col;
	enum dir{right,down,left,up} direction;
	row =0;
	col =0;
	direction = right;
	upbound =leftbound =0;
	rightbound=3-1;
	downbound = 3-1;
	while(1)
	{
		printf("%d ",data[row][col]);
		if(direction ==  right)
		{		
				if(col <rightbound)
				{
					++col;
				}
				else
				{
					if(upbound == downbound)
					{
						break;
					}
					++row;
					direction = down;
					++upbound;
				}						
		}
		else if(direction == down)
		{
			if(row < downbound)
			{
				++row;
			}
			else
			{
				if(leftbound == rightbound)
				{
					break;
				}
				--col;
				direction = left;
				--rightbound;
			}
		} 
		else if(direction == left)
		{
			if(leftbound <col)
			{
				--col;
			}
			else
			{
				if(upbound == downbound)
				{
					break;
				}
				--row;
				direction = up;
				--downbound;
			}
		}
		else if(direction == up)
		{
			if(upbound <row)
			{
				--row;
			}
			else
			{
				if(leftbound == rightbound)
				{
					break;
				}
				++col;
				direction = left;
				++leftbound;
			}
		}
	
	}
	return 0;
}