从文本文件中提取特定行 [英] Extract specific lines from text file

问题描述

我有一个结构化的文本文件，其中包含客户信息，这里有一些示例数据
236，Janet，Stones，26300,19/10/2010
203，Linda，Phiri，15000,23/10/2010
150，Harry，Banda，16700,09/08/2010
418，Bridget，Tatianna，16/09/2010
210，约瑟夫，阿隆佐，2900,23/10/2010
我希望从此文本文件中提取包含特定日期的行，例如，我想提取所有包含"23/10/2010"的行
所以我写了下面的代码

I have a structured text file which contains customer information here iz a few sample data
236,Janet, Stones,26300,19/10/2010
203,Linda,Phiri,15000,23/10/2010
150,Harry,Banda,16700,09/08/2010
418,Bridget, Tatianna,16/09/2010
210,Joseph,Alonzo,2900,23/10/2010
from this text file i wish to extract lines which contain a specific date so for example I want to extract all the lines containing ''23/10/2010''
so i wrote the following code

static void main(string[] args)
{
  string path = @"C:\customers.txt";
  StringBuilder buffer = new StringBuilder();
  using (StreamReader = new StreamReader(path)){
  while(sr.Peek() >=0){
  if(Regex.IsMatch(sr.Readline(), "23/10/2010"))
  buffer.Append(sr.ReadLine());

}
}
Console.WriteLine(buffer.ToString());
}

当我运行它而不是得到两行时，我只得到一个，更奇怪的是它仅输出第二行而不是第一行，所以在这种情况下，我的结果是210，Joseph，Alonzo，2900,23/10/2010和如果一行中只有1个发生在23/10/2010，那么我得到的结果是空的，所以我真的需要这个帮助！感谢

when i run this instead of getting two lines i get only one whats even more strange is it only output the second line and not the first line so my result in this case is 210,Joseph,Alonzo,2900,23/10/2010 and if only 1 occurence had 23/10/2010 in the line then im getting empty results so I really need help with this one! Thanks

推荐答案

这非常简单，因此您不需要使用正则表达式.这样的事情会更容易:

This is fairly simple, so you don''t need to use regular expressions. Something like this would be easier:

string[] lines = File.ReadAllLines(filePath);

IEnumerable<string> selectLines = lines.Where(line => line.EndsWith("23/10/2010"));

foreach (var item in selectLines)
{
    Console.WriteLine(item);
}

您可以使用

字符串.包含链接 [链接 [

You could use

String.Contains link[^]

or

String.IndexOf link[^] - IndexOf should return >= 0 for the line to contain the string you are searching for

instead of Regex matching, simple and straight-forward

string stringToSearch = @"<your_string>";
string[] lines = File.ReadAllLines(@"path_to_your_file");
foreach (string line in lines)
{
    if (line.Contains(stringToSearch))
    {
    Console.WriteLine(line);
    }
}

或

or

string stringToSearch = @"<your_string>";
string[] lines = File.ReadAllLines(@"path_to_your_file");
foreach (string line in lines)
{
    if (line.IndexOf(stringToSearch) >= 0)
    {
    Console.WriteLine(line);
    }
}

我没有建议完成任务的其他方法，而是着重介绍了为什么您的代码无法正常工作.


我使用的是C ++，而不是C#，但是通过调试代码来查看问题出在哪里，这很简单.这些更改是微不足道的，在此我将不予赘述.仅将工作代码粘贴到此处.

为了分隔输出中的行，我尝试了C转义序列"\ r"和"\ n"，但我想C#使用了一些不同的方法.

Instead of suggesting alternate ways of accomplishing the task I focussed on why your code isn''t working.


I work with C++, not C# but its a simple matter to see whats wrong by debugging the code. The changes are trivial and I won''t mention them here; just the working code is pasted here.

To separate lines in the output I tried the C escape sequence "\r" and "\n" but I guess C# uses some different method.

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {


            string path = @"h:\customers.txt";
            StringBuilder buffer = new StringBuilder();
            using (StreamReader sr = new StreamReader(path))
            {
                while(sr.Peek() >=0) {
                    String str = sr.ReadLine();
                    if(Regex.IsMatch(str, "23/10/2010"))
                        buffer.Append(str + @"\n");
                }
            }
            Console.WriteLine(buffer.ToString());
        }
    }
}

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