C#打印正三角、倒三角、平行四边形

首先看下配置：
请添加图片描述

1.打印正三角

  int line_num = Convert.ToInt32(txt_hs.Text.Trim());//需要输出的行数
            string str = "";//存放打印内容

            for (int i = 1; i <= line_num; i++)
            {
                foreach (var c in Enumerable.Repeat(" ", line_num - i))//每行打印多少个空格
                    str +=c;
                foreach (var s in Enumerable.Repeat("* ", i))//每行打印多少个*
                    str += s;
                str += "\n";
            }
            lbl_jm.Text = str;

得到的结果：

2.打印倒三角

  int line_num = Convert.ToInt32(txt_hs.Text.Trim());
            string str = "";

            for (int i = 0; i < line_num+1; i++)
            {
                foreach (var c in Enumerable.Repeat(" ", i))
                    str += c;
                foreach (var s in Enumerable.Repeat("* ", line_num - i))
                    str += s;
                str += "\n";
            }
            lbl_jm.Text = str;

得到的结果：

3.打印平行四边形

 int line_num = Convert.ToInt32(txt_hs.Text.Trim());
            string str = "";

            for (int i = 1; i <= line_num; i++)
            {
                foreach (var c in Enumerable.Repeat(" ", i ))
                    str += c;
                foreach (var s in Enumerable.Repeat("* ",line_num))
                    str += s;
                str += "\n";
            }
            lbl_jm.Text = str;

得到的结果：