LINQ 和字符串

LINQ 可用于查询和转换字符串和字符串集合。它对文本文件中的半结构化数据尤其有用。LINQ 查询可与传统的字符串函数和正则表达式结合使用。例如，可以使用 Split 或 Split 方法来创建字符串数组，然后可以使用 LINQ 来查询或修改此数组。可以在 LINQ 查询的 where 子句中使用 IsMatch 方法。可以使用 LINQ 来查询或修改由正则表达式返回的 MatchCollection 结果。

一、LINQ查询匹配给定的字符

using System;
using System.Linq;
using System.Collections.Generic;
using System.Collections;

/// <summary>
///Class1 学习linq

/// </summary>
public class Class1
{
 public Class1()
 {
  //
  //TODO: 在此处添加构造函数逻辑
  //
 }
    public string LinqToString()
    {
          string text = @"Historically, the world of data and the world of objects" +
          @" have not been well integrated. Programmers work in C# or Visual Basic" +
          @" and also in SQL or XQuery. On the one side are concepts such as classes," +
          @" objects, fields, inheritance, and .NET Framework APIs. On the other side" +
          @" are tables, columns, rows, nodes, and separate languages for dealing with" +
          @" them. Data types often require translation between the two worlds; there are" +
          @" different standard functions. Because the object world has no notion of query, a" +
          @" query can only be represented as a string without compile-time type checking or" +
          @" IntelliSense support in the IDE. Transferring data from SQL tables or XML trees to" +
          @" objects in memory is often tedious and error-prone.";

        string searchTerm = "data";

        //将内容拆分成数组
        string[] source = text.Split(new char[] { '.', '?', '!', ' ', ';', ':', ',' }, StringSplitOptions.RemoveEmptyEntries);

        //从数组里查询符合条件的数据
        var matchQuery = from s in source where s.IndexOf('a')==0 orderby s ascending select s ;

      
        int wordCount = matchQuery.Count();
        string str="";
        foreach(string a in matchQuery)
            str+=a+",";
        //返回查询后的结果
        return str+":::"+wordCount;

    }

   
}