using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
namespace WindowsFormsApplication4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        //时间按钮点击事件
        private void 时间日期ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            textBox1.Text = DateTime.Now.ToString("HH:mm yyyy/MM/dd");
        }
        //撤销按钮点击事件
        private void 撤消UToolStripMenuItem_Click(object sender, EventArgs e)
        {
            textBox1.Undo();
        }
        //剪切按钮事件
        private void 剪切TToolStripMenuItem_Click(object sender, EventArgs e)
        {
            textBox1.Cut();
        }
        //复制按钮事件
        private void 复制CToolStripMenuItem_Click(object sender, EventArgs e)
        {
            textBox1.Copy();
        }
        //粘贴按钮事件
        private void 粘贴PToolStripMenuItem_Click(object sender, EventArgs e)
        {
            textBox1.Paste();
        }
        //删除按钮事件
        private void toolStripMenuItem3_Click(object sender, EventArgs e)
        {
            textBox1.SelectedText = "";
        }
        //全选按钮事件
        private void 全选AToolStripMenuItem_Click(object sender, EventArgs e)
        {
            textBox1.SelectAll();
        }
        //查找按钮事件
        private void toolStripMenuItem1_Click(object sender, EventArgs e)
        {
            Form2 f2 = new Form2(this);
            f2.Owner = this;
            f2.Show();
        }
        //替换按钮点击事件
        private void 替换ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form3 f3 = new Form3(this);
            f3.Owner = this;
            f3.Show();
        }
        //换行按钮点击事件
        private void 自动换行ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (textBox1.WordWrap)
            {
                textBox1.WordWrap = false;
                textBox1.ScrollBars = ScrollBars.Both;
            }
            else
            {
                textBox1.WordWrap = true;
                textBox1.ScrollBars = ScrollBars.Vertical;
            }
        }
        //字体按钮点击事件
        private void 字体ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            DialogResult dll = fontDialog1.ShowDialog();
            if (dll == DialogResult.OK)
            {
                textBox1.Font = fontDialog1.Font;
            }
        }
        //颜色按钮点击事件
        private void 字体ToolStripMenuItem1_Click(object sender, EventArgs e)
        {
            DialogResult dll = colorDialog1.ShowDialog();
            if (dll == DialogResult.OK)
            {
                textBox1.ForeColor = colorDialog1.Color;
            }
        }
        //打开按钮点击事件
        private void 打开OToolStripMenuItem_Click(object sender, EventArgs e)
        {
            openFileDialog1.Filter = "文本文件|*.txt";//选择文件能打开格式,多个"文本文件|*.txt|文本文档|*.doc|所有文件|*.*"
            DialogResult dll = openFileDialog1.ShowDialog();
            if (dll == DialogResult.OK)
            {                                     //打开文件路径,以文件的默认编码方式打开
                StreamReader sr = new StreamReader(openFileDialog1.FileName, Encoding.Default);
                textBox1.Text = sr.ReadToEnd();
            }
        }
        string save = "";
        private void 保存SToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (save == "")//判断有没有保存路径
            {
                DialogResult dll = saveFileDialog1.ShowDialog();
                if (dll == DialogResult.OK)
                {
                    StreamWriter sw = new StreamWriter(saveFileDialog1.FileName);
                    sw.Write(textBox1.Text);
                    sw.Flush();
                    save = saveFileDialog1.FileName;
                    sw.Close();
                }
            }
            else
            {
                StreamWriter sw = new StreamWriter(saveFileDialog1.FileName);
                sw.Write(textBox1.Text);
                sw.Flush();
                sw.Close();
            }
        }
        //底部菜单栏
        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            toolStripLabel1.Text = "字数:" + textBox1.TextLength;
            toolStripLabel2.Text = "行数" + (textBox1.GetLineFromCharIndex(textBox1.TextLength)+1);
        }

    }
}

form1

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication4
{
    public partial class Form2 : Form
    {
        Form1 F1 = null;
        public Form2(Form1 f1)
        {
            InitializeComponent();
            F1 = f1;
        }
        int z = 0;
        private void button1_Click(object sender, EventArgs e)
        {
            string s = F1.textBox1.Text;
            if (z < 0)
            {
                z = 0;
            }
            z = s.IndexOf(textBox1.Text, z);
            if (z >= 0)
            {

                F1.textBox1.Select(z, textBox1.TextLength);
                F1.Focus();
                z++;
            }
            else
            {
                MessageBox.Show("找不到" + "\"" + textBox1.Text + "\"");
            }
        }
    }
}

form2

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication4
{
    public partial class Form3 : Form
    {
        Form1 F1 = null;
        public Form3(Form1 f1)
        {
            InitializeComponent();
            F1 = f1;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int z = 0;
            string s = F1.textBox1.Text;
            if (s.IndexOf(textBox1.Text, z) < 0)
            {
                MessageBox.Show("找不到" + "\"" + textBox1.Text + "\"");
            }
            for (; ; )
            {
                if (z < 0)
                {
                    F1.Focus();
                    break;
                }
                z = s.IndexOf(textBox1.Text, z);
                if (z >= 0)
                {
                    F1.textBox1.Select(z, textBox1.TextLength);
                    F1.textBox1.SelectedText = textBox2.Text;
                    z++;
                }
            }
        }
    }
}

form3