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  1. using System;
  2. using System.Collections.Generic;
  3. using System.ComponentModel;
  4. using System.Data;
  5. using System.Drawing;
  6. using System.Linq;
  7. using System.Text;
  8. using System.Threading.Tasks;
  9. using System.Windows.Forms;
  10.  
  11. namespace WindowsFormsApplication1
  12. {
  13.     public partial class Form1 : Form
  14.     {
  15.         public Form1()
  16.         {
  17.             InitializeComponent();
  18.         }
  19.  
  20.         private Label lbl = null;
  21.         private void Form1_Load(object sender, EventArgs e)
  22.         {
  23.             lbl = new Label();
  24.             lbl.Text = "入力してください。";
  25.             lbl.Cursor = Cursors.IBeam;
  26.             lbl.Click += lbl_Click;
  27.             lbl.Anchor = AnchorStyles.Right;
  28.             lbl.AutoSize = true;
  29.             lbl.BackColor = Color.Transparent;
  30.             lbl.ForeColor = Color.Gray;
  31.             textBox1.Enter += lbl_Click;
  32.             textBox1.Leave += textBox1_Leave;
  33.             textBox1.Controls.Add(lbl);
  34.         }
  35.  
  36.         void textBox1_Leave(object sender, EventArgs e)
  37.         {
  38.             if (string.IsNullOrEmpty(textBox1.Text))
  39.             {
  40.                 lbl.Visible = true;
  41.             }
  42.         }
  43.  
  44.  
  45.         void lbl_Click(object sender, EventArgs e)
  46.         {
  47.             this.lbl.Visible = false;
  48.             this.textBox1.Focus();
  49.         }
  50.     }
  51. }
  52.  
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https://ideone.com/YdIY2
language:
C# (gmcs 5.20.1)
created:
12 years ago
visibility:
public

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