C#之String学习一

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace StringDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            string str1 = "hello ";
            string str2 = "rose_girls !";

            //Compare
            int result = String.Compare(str1, str2);
            Console.WriteLine("compare result is " + result);


            /**********************Concat(字符串连接)****************************/
            //耗内存 耗时间 
            string contact = String.Concat(str1, str2);
            Console.WriteLine("contact  is: " + contact);


            /**********************CopyTo(数据拷贝到指定源)****************************/
            char[] tmpCha = new char[contact.Length];
            contact.CopyTo(0, tmpCha, 0, contact.Length);
            Console.Write("CopyTo is: ");
            foreach (char c in tmpCha) {
                Console.Write(c);
            }
            Console.WriteLine();


            /**********************Format(格式化)****************************/
            //默认格式化小数点后面保留两位小数
            string format = string.Format("{0:C}", 15.34);
            Console.WriteLine("format one dot is: " + format);
            //截取会自动四舍五入 保留一位
            format = string.Format("{0:C1}", 15.34);
            Console.WriteLine("format two dot is: " + format);

            /**********************IndexOf(找到单个字符出现的位置)****************************/
            //获取在str中第一次出现l的位置
            int index = str1.IndexOf('l');
            Console.WriteLine("IndexOf index is: " + index);


            /**********************IndexOfAny(找到当个字符或者字符数组的位置)****************************/
            tmpCha = "ro".ToCharArray();
            //在str2中找到第一次出现tmpcha中内容的位置
            index = str2.IndexOfAny(tmpCha);
            Console.WriteLine("IndexOf IndexOfAny is: " + index);


            /**********************Insert(在指定位置插入字符串)****************************/
            //在str2中插入"!!"字符串，返回插入后的字符串  不会改变str2本身的值
            string tmpStr = str2.Insert(str2.Length - 1, "!!");
            Console.WriteLine("Insert is: " + str2);
            Console.WriteLine("Insert return is: " + tmpStr);


            /**********************Join(合并字符串)****************************/
            string join = string.Join("!","bbb","aaa","ccc");
            Console.WriteLine("Join is: " + join);

            /**********************PadLeft、PadRight(字符串左右填充)****************************/
            //30:str2字符串的总长度 ‘l':用来填充的字符
            string padLeft = str2.PadLeft(30, 'l');
            string padRight = str2.PadRight(100, 'r');
            Console.WriteLine("PadLeft is " + str2 + "  " + padLeft);


            /**********************Replace(字符串替换)****************************/
            tmpStr = str1.Replace('l', 'L');
            Console.WriteLine("Replace is: " + tmpStr);


            /**********************Split(字符串分离)****************************/
            string[] split = str2.Split('_');
            Console.WriteLine("Split  is: " + str2 + " split[0] = " + split[0] + "  split[1] = " + split[1]);


            /**********************Substring(子字符串)****************************/
            tmpStr = str2.Substring(0, str2.Length - 2);
            Console.WriteLine("Substring is:" + str2 + "  tmpStr: " + tmpStr);


            /**********************ToUpper、ToLower(大小写转换)****************************/
            tmpStr = str2.ToUpper();
            Console.WriteLine("ToUpper is:" + tmpStr);
            tmpStr = tmpStr.ToLower();
            Console.WriteLine("ToLower is:" + tmpStr);


            /**********************Trim(删除首尾空白)****************************/
            tmpStr = "   " + tmpStr + "   ";
            Console.WriteLine("tmpStr is:" + tmpStr);
            Console.WriteLine("Trim is:" + tmpStr.Trim());
            

            Console.ReadLine();

        }
    }
}