使用正则表达式提取文本数据到内存是很方便的技术，下面通过一个例子介绍一下如何使用正则表达式提取文本

文本中内容格式

1,2,3,4,5

2,2,2,2,2

3,3,3,3,3

C#代码如下

public List<List<string>> GetDataCSV(string path)
{string pattern = @"\d+";List<List<string>> data = new List<List<string>>();using(StreamReader sr = new StreamReader(@path, Encoding.GetEncoding("GB2312"))){string nextline;MatchCollection myMatches;while((nextline = sr.ReadLine()) != null ){myMatches = Regex.Matches(nextline, pattern);List<string> rowdata = new List<string>(); ;foreach(Match nextmatch in myMatches){rowdata.Add(nextmatch.Value);}data.Add(rowdata);}//消除最后的空行for(int i=data.Count-1;i>=0;i--){if(data[i].Count ==0){data.Remove(data[i]);}else{break;}}  }return data;
}

上面代码试用标准格式，逗号间都有数据，此外逗号间无数据如

1,2,3,4

2,,3,3

3,3,3,3

方法如下：

public List<List<string>> GetDataFromCSV(string path)
{List<List<string>> data = new List<List<string>>();using(StreamReader sr = new StreamReader(@path, Encoding.GetEncoding("GB2312"))){string nextline;while((nextline = sr.ReadLine()) != null ){List<string> row = new List<string>();char[] charArray = nextline.ToCharArray();int flag = 0;for (int i = 0; i < charArray.Length;i++){if(charArray[i] != ',' && i != (charArray.Length -1)){continue;}else{if(flag == i){row.Add("-1");//若空值赋值-1，此处赋值可自行定义flag = i + 1;if(i == charArray.Length - 1)//若最后一个为逗号，需在加一个空值，即添加-1代表空{row.Add("-1");}}else{string s;if(i == charArray.Length - 1)//最后一个数时提取字符串length=i-flag + 1{s = nextline.Substring(flag, i - flag + 1);}else{s = nextline.Substring(flag, i - flag);}flag = i + 1;row.Add(s);}}}data.Add(row);}//消除最后的空行for(int i=data.Count-1;i>=0;i--){if(data[i].Count ==0){data.Remove(data[i]);}else{break;}}  }return data;
}