如何检查 streamread 行中是否有 4 个或更多空格

Question

我正在尝试为文本文件中的管道替换 space，但如果有 4 个或更多 space。到目前为止我的代码是：

string MyNewFile;
using (StreamWriter sWriter = new StreamWriter(MyNewFile, false, encoding, 1))
{
    using (StreamReader sReplaceReader = new StreamReader(myFile))
    {
        string line, textLine = "";

        while ((line = sReplaceReader.ReadLine()) != null)
        {
            if (line.Contains("    ")>=4 )//if contains 4 or more spaces
            {
                textLine = line.Replace("    ", "|");
            }

            sWriter.WriteLine(textLine);
        }
    } 
}

我的想法是通过方法中的参数获取 space 的数量，但是，我不知道如何输入 line.Replace(4.space 或 4 char.IsWhiteSpace()，分隔符）。我希望你解释得很好

Answer 1

正则表达式是完成这项工作的好工具。试试这个：

string MyNewFile;
using (StreamWriter sWriter = new StreamWriter(MyNewFile, false, encoding, 1))
{
    using (StreamReader sReplaceReader = new StreamReader(myFile))
    {
        string line, textLine = "";

        while ((line = sReplaceReader.ReadLine()) != null)
        {
            RegexOptions options = RegexOptions.None;
            Regex regex = new Regex("[ ]{4,}", options);     
            string textLine = regex.Replace(line, "|");

            sWriter.WriteLine(textLine);
        }
    } 
}

这与这里的答案非常相似：How do I replace multiple spaces with a single space in C#?

Answer 2

您可以使用 RegEx 来执行此操作，并且可以创建一个接受变量输入的方法（因此您可以指定要替换的字符和连续实例的最小数量，以及替换字符串：

public static string ReplaceConsecutiveCharacters(string input, char search,
    int minConsecutiveCount, string replace)
{
    return input == null
        ? null
        : new Regex($"[{search}]{{{minConsecutiveCount},}}", RegexOptions.None)
            .Replace(input, replace);
}

然后可以这样调用：

static void Main()
{
    var testStrings = new List<string>
    {
        "Has spaces      scattered          throughout  the   body    .",
        "      starts with spaces and ends with spaces         "
    };

    foreach (var testString in testStrings)
    {
        var result = ReplaceConsecutiveCharacters(testString, ' ', 4, "|");
        Console.WriteLine($"'{testString}' => '{result}'");
    }

    GetKeyFromUser("\nDone! Press any key to exit...");
}

输出

Answer 3

My idea is to get the number of spaces by a parameter in a method but, I dont know how to put something like line.Replace(4.space or 4 char.IsWhiteSpace(), separator)

private string SpacesToDelimiter(string input, int numSpaces  = 4, string delimiter = "|")
{
    string target = new String(' ', numSpaces);
    return input.Replace(target, delimiter);
}

这样称呼它：

string MyNewFile = "...";
using (StreamWriter sWriter = new StreamWriter(MyNewFile, false, encoding, 1))
{
    foreach(string line in File.ReadLines(myFile))
    {
         sWriter.WriteLine(SpacesToDelimiter(line));
    }
}

如何检查 streamread 行中是否有 4 个或更多空格

how to check if there are 4 or more spaces in streamread line

c#

char

streamreader