从9x9矩阵中抽取中间菱形区域打印 - perl

起因： 源自于c的练习题，打印diamond，因为perl不需编译，方便调试，故先用perl实现一下

关键： 没有想到好的思路，只能借助于上一篇打印上下三角矩阵的方法，把菱形拆成上下左右4个三角矩阵区域来实现。

#!/usr/bin/perl -w
use strict;
## ------------------------------- diamond -----------------------------------------
## upper peak
for my $row (reverse(1..9))
{
    ## upper left
    for my $col(1..9)
    {
        if($col >= $row)
        {
            print "* ";
        }
        else
        {
            print "  ";
        }
    }

    ## upper right
    for my $col(reverse(1..9))
    {
        if($col > $row)
        {
            print "* ";
        }
        else
        {
            print "  ";
        }
    }
    print "\n";
}

## lower peak
for my $row (2..9)
{
    print "  ";
    ## lower left
    for my $col(2..9)
    {
        if($col >= $row)
        {
            print "* ";
        }
        else
        {
            print "  ";
        }
    }

    ## lower right
    for my $col(reverse(2..9))
    {
        if($col > $row)
        {
            print "* ";
        }
        else
        {
            print "  ";
        }
    }
    print "\n";
}

输出：