C#比较两个排序列表并输出到文件 [英] C# Comparing two sorted lists and outputting to a file

问题描述

我正在尝试将编译后的字符串列表与主列表进行比较，然后将它们打印到文本文件中.我遇到的问题是可打印列表仍然为空.如何填充第三个列表?而且，这是否正确使用了List<>，如果不是，我应该使用什么?

I'm trying to compare a list of strings compiled together against a master list and print them out to a text file. The problem I'm having is the printable list remains empty. How do I populate the third list? And, is this a proper use of List<>, if not, what should I use?

编辑:很抱歉，在运行此方法之前，textInput和textCompare从两个文件中读取并填充了7个字符的字符串:一个是从文本文件中提取的，另一个来自Excel工作表.然后，我删除所有空值，并尝试将两个列表与listA.intersects(listB)进行比较. MSDN提到要使相交起作用，需要对其进行枚举，这就是为什么我将其放在foreach中的原因.

Edit: Sorry about that, prior to this method running, textInput and textCompare read from two files and are populated with strings 7 characters in length: one pulled from a text file, the other from an excel sheet. I then remove any nulls, and attempt to compare the two lists with listA.intersects(listB). MSDN mentioned it need to be enumerated through for the intersects to work, which is why I put it in a foreach.

void Compare()
{
    List<string> matches = new List<string>();

    textInput.Sort();
    textCompare.Sort();

    progressBar.Maximum = textInput.Count;

    int increment = 0;

    for (int i = textCompare.Count - 1; i >= 0; i--)
    {
        if (textCompare[i] == null)
        {
            textCompare.RemoveAt(i);
        }
    }

    foreach (string item in textInput)
    {
        matches = textInput.Intersect(textCompare).ToList();
        increment++;
        progressBar.Value = increment;
    }

    //A break point placed on the foreach reveals matches is empty.
    foreach (object match in matches)
    {
        streamWriter.WriteLine(match);
    }
    doneLabel.Text = "Done!";
} 

推荐答案

从您注释的描述中可以做到这一点:

From the description in your comment this would do it:

var textOutput = textCompare.Where(s => !string.IsNullOrEmpty(s))
                            .Intersect(textInput)
                            .OrderBy(s => s);

File.WriteAllLines("outputfile.txt", textOutput);

请注意，如果主列表"textInput"中没有空字符串(很可能没有)，则可以删除.Where()条件.另外，如果顺序无关紧要，请删除.OrderBy()，然后结束此操作:

Note that you can remove the .Where() condition provided you don't have empty strings in your masterlist "textInput" (very likely there aren't). Also, if order doesn't matter remove the .OrderBy(), you end up with this then:

var textOutput = textCompare.Intersect(textInput);
File.WriteAllLines("outputfile.txt", textOutput);

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