cscの作法 その495

概要

cscの作法、調べてみた。
練習問題やってみた。

練習問題

DataTableを、CSV出力せよ。

写真

サンプルコード

using System;
using System.Windows.Forms;
using System.Drawing;
using System.Data;
using System.IO;
using System.Text;

class form1: Form {
	ComboBox comboBox1;
	DataTable dt;
	DataGridView gd0;
	form1() {
		Text = "csv out";
		ClientSize = new Size(400, 300);
		comboBox1 = new ComboBox();
		comboBox1.Location = new Point(120, 10);
		comboBox1.Size = new Size(100, 25);
		comboBox1.Items.Add("");
		comboBox1.Items.Add("赤");
		comboBox1.Items.Add("黄");
		comboBox1.Items.Add("紫");
		comboBox1.Items.Add("橙");
		comboBox1.Items.Add("緑");
		comboBox1.SelectedIndex = 0;
		comboBox1.SelectedValueChanged += comboBox1_SelectedIndexChanged;
		dt = new DataTable();
		dt.Columns.Add("id", typeof(int));
		dt.Columns.Add("Iro", typeof(string));
		dt.Columns.Add("Name", typeof(string));
		dt.Rows.Add(1, "赤", "りんご");
		dt.Rows.Add(2, "黄", "バナナ");
		dt.Rows.Add(3, "黄", "レモン");
		dt.Rows.Add(4, "赤", "トマト");
		dt.Rows.Add(5, "紫", "ぶどう");
		dt.Rows.Add(6, "橙", "みかん");
		dt.Rows.Add(7, "橙", "柿");
		dt.Rows.Add(8, "緑", "めろん");
		gd0 = new DataGridView();
		gd0.Location = new Point(20, 40);
		gd0.Size = new Size(350, 250);
		gd0.DataSource = dt;
		Button btn1 = new Button();
		btn1.Location = new Point(250, 10);
		btn1.Text = "csv出力";
		btn1.Click += btn1_Click;
		Controls.AddRange(new Control[] {
			comboBox1,
			btn1,
			gd0
		});
	}
	private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) {
		string str = "Iro = '" + comboBox1.SelectedItem.ToString() + "'";
		DataTable _newFilteredDataTable = dt.Select(str).CopyToDataTable();
		gd0.DataSource = _newFilteredDataTable;
	}
	void btn1_Click(object sender, System.EventArgs e) {
		Encoding enc = Encoding.GetEncoding("Shift_JIS");
		using (StreamWriter sr = new StreamWriter("dt8.csv", true, enc))
		{
			foreach (DataRow row in dt.Rows)
			{
				sr.WriteLine(string.Join(",", row.ItemArray));
			}
		}
	}
	[STAThread]
	public static void Main() {
		Application.Run(new form1());
	}
}

実行結果

>type dt8.csv
1,赤,りんご
2,黄,バナナ
3,黄,レモン
4,赤,トマト
5,紫,ぶどう
6,橙,みかん
7,橙,柿
8,緑,めろん

以上。