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

namespace c7_1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button4_Click(object sender, EventArgs e)
        {
            string a1 = label1.Text;
            int len1 = a1.Length;
            textBox1.Text = len1.ToString();
        }

        private void button5_Click(object sender, EventArgs e)
        {
            string a1 = label1.Text;
            string a2 = a1.ToUpper();
            textBox1.Text = a2;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //字串尋找：IndexOf()
            //IndexOf("要尋找的內容"):找到這個字元或字串第一次出現的索引位置，如果找不到會回傳 - 1。 常用
            //LastIndexOf("要找的內容"):找到這個字元或字串最後一次出現的索引位置，如果找不到會回傳 - 1.

            string a1 = label1.Text;
            int pos = a1.IndexOf("good");
            if (pos == -1) 
                textBox1.Text = "找不到";
            else 
                textBox1.Text = "找到了，位置在：" + pos.ToString();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            string a1 = label1.Text;
            int pos = a1.IndexOf("c++");
            if (pos == -1)
                textBox1.Text = "找不到";
            else
                textBox1.Text = "找到了，位置在：" + pos.ToString();
        }

        private void button6_Click(object sender, EventArgs e)
        {
            string a1 = label1.Text;
            string a2 = a1.Replace("c#", "java");
            textBox1.Text = a2;
            
        }
    }
}