转 String常用方法回顾

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

namespace StringTest
{
    class Program
    {
        static void Main(string[] args)
        {
            //格式化输出
            Console.WriteLine(DateTime.Now.ToString("yyyy-MM-dd"));
            Console.WriteLine(string.Format("{0} 在{1:yyyy年MM月dd日}到达北京.", "小王", DateTime.Now));
            double d = 123.456789;
            Console.WriteLine(d.ToString("C3")); 

            string s = "1,2,3,4,5,6";
            string[] s2 = s.Split(','); //注意是''
            foreach (string i in s2)
            {
                Console.WriteLine(i);
            }

            //指定符号连接
            string join = string.Join("-", s2);
            Console.WriteLine(join);

            //String 与 StringBuilder 效率比较
            DateTime before = DateTime.Now;
            string a = "aaa";
            for (int i = 0; i < 20000; i++)
            {
                a += i;
            }
            Console.WriteLine("String相加循环所花费的时间为{0}", DateTime.Now - before);

            DateTime start = DateTime.Now;
            StringBuilder sb = new StringBuilder("aaa");
            for (int i = 0; i < 20000; i++)
            {
                sb.Append(i);
            }
            Console.WriteLine("StringBuilder相加循环所花费的时间为{0}", DateTime.Now - start);

            //类型转换
            string st = "123e";
            int dd;
            if (int.TryParse(st, out dd))
            {
                Console.WriteLine(dd);
            }
            else
            {
                Console.WriteLine("请输入正确的数字!");
            }

            //判断字符串是否为空
            string em = "";
            if (string.IsNullOrEmpty(em))
            {
                Console.WriteLine("em是空字符串!");
            }

            //截取
            string tr = "---bcd---";
            string end = tr.Trim('-');
            Console.WriteLine(string.Format("{0}:长度为{1}", end, end.Length));

            //比较  ToUpper()经过优化,效率比较高
            string yz = "aBC";
            string sz = "Abc";
            Console.WriteLine(yz.ToUpper() == sz.ToUpper());
            //MVP推荐使用
            Console.WriteLine(string.Compare(yz, sz, true) == 0);

            //正则表达式
            Regex re = new Regex("[a-zA-Z]+", RegexOptions.None);
            string[] lines = re.Split("12r4t");
            foreach (string line in lines)
            {
                Console.WriteLine(line);
            }

            MatchCollection mc = re.Matches("t45yu");
            foreach (Match ma in mc)
            {
                Console.WriteLine(ma);
            }
            Console.ReadKey();
        }
    }
}

看到别人总结的,自己也回顾一下.