c#學習筆記之字串和Regex

標籤：

一、字串

c#中提供了一系列關於string類型的值的操作，便於我們對string進行各種類型的操作，例如比較，轉化成字串等等

eg：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Text.RegularExpressions;using System.Threading.Tasks;namespace stringand{    class Program    {        static void Main(string[] args)        {            int a = 554;            string stringa = a.ToString();//把a的內容以字串形式輸出            string b = "qwer";            string c = "asdf";            Console.WriteLine(b.CompareTo(c));//比較string b和c的大小，若為正數，則前者大            //若為0，則兩者相等，若為負數，則後者大，此處返回1            Console.WriteLine(string.Compare(b,c));// 返回1        }    }}

另外，附上一些string類包含的方法

 

二、Regex

C#中為Regex的使用提供了非常強大的功能，這就是Regex類。這個包包含於System.Text.RegularExpressions命名空間下面。

eg：

Regex regex = new Regex(@"\d");//  \d為匹配數字

regex.IsMatch("abc"); //傳回值為false，字串中未包含數字
regex.IsMatch("abc3abc"); //傳回值為true，因為字串中包含了數字

regex.Matches("abc123abc").Count;//返回3，因為匹配到3個數字

regex.Match("abc123abc").Value;// 返回為1，因為是匹配到第一個數位值

 

下面是在vs中的一些執行個體：

string s1 = "One,Two,Three Liberty Associates, Inc.";             Regex theRegex = new Regex(" |, |,");             StringBuilder sBuilder = new StringBuilder();  int id = 1;             foreach (string subString in theRegex.Split(s1))             {                 sBuilder.AppendFormat("{0}: {1}\n", id++, subString);             }             Console.WriteLine("{0}", sBuilder);

 

 string string1 = "This is a test string";            // find any nonwhitespace followed by whitespa             Regex theReg = new Regex(@"(\S+)\s");             // get the collection of matches             MatchCollection theMatches = theReg.Matches(string1);              // iterate through the collection             foreach (Match theMatch in theMatches)             {               Console.WriteLine("theMatch.Length: {0}", theMatch.Length);               if (theMatch.Length != 0)                  {                     Console.WriteLine("theMatch: {0}", theMatch.ToString( ));                 }             }

 

結果為：

 

 string string2 = "04:03:27 127.0.0.0 LibertyAssociates.com " +                 "04:03:28 127.0.0.0 foo.com " +  "04:03:29 127.0.0.0 bar.com ";              Regex theReg2 = new Regex(@"(?<time>(\d|\:)+)\s"                 +@"(?<ip>(\d|\.)+)\s" + @"(?<site>\S+)");//  \S ：與任何非空白的字元匹配。            MatchCollection theMatches2 = theReg2.Matches(string2);          foreach (Match theMatch in theMatches2)         {// iterate through the collection              if (theMatch.Length != 0)              {                  Console.WriteLine("\ntheMatch: {0}", theMatch.ToString());                 Console.WriteLine("time:{0}",theMatch.Groups["time"]);                  Console.WriteLine("ip: {0}", theMatch.Groups["ip"]);                  Console.WriteLine("site: {0}", theMatch.Groups["site"]);             }          }

結果為：

 

c#學習筆記之字串和Regex