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 将字符串转换为大写小写
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
label1.Text = "输入字符串";
label2.Text = "转换后的字符串";
button1.Text = "确认转换";
radioButton1.Text = "大写";
radioButton2.Text = "小写";
radioButton1.Checked = true;
}
private void button1_Click(object sender, EventArgs e)
{
if (textBox1.Text == " ") //判断文本框是否为空
{
MessageBox.Show("请输入字符串");
}
if(radioButton1.Checked==true)
{
textBox2.Text = textBox1.Text.ToUpper(); //ToUpper()方法将小写字母转换成大写字母
}
else
{
textBox2.Text = textBox1.Text.ToLower(); //ToUpper()方法将大写字母转换成小写字母
}
}
private void textBox1_KeyPress(object sender, KeyPressEventArgs e) //用到了textbox的keypress事件,用来判断输入的是否为想要的字母,如果不是,将禁止输入
{
if ((e.KeyChar >= '1' && e.KeyChar <= '9' )||( e.KeyChar >= 'a' && e.KeyChar <= 'z' )|| (e.KeyChar >= 'A' && e.KeyChar <= 'Z'))
{
e.Handled = false; //e.handled=false表示没有处理过,同意输入
}
else
{
e.Handled = true; //e.handled=false表示处理过了,禁止输入
}
}
}
}
运行结果