Question

下面的文本文件示例

text_file a

Text_ID“441124_aad0656_1234”

Text_FILE_NAME

我想只保留字符串“1234”的最后一个索引

StreamReader streamReader = new StreamReader(text);
string text2;
while ((text2 = streamReader.ReadLine()) != null)
{
    num++;
    string[] array3 = text2.Split(new char[0]);
    if (array3[0] == "Text_ID")
    {
        string[] array4 = array3[1].Split(new char[] {'_'});
        string value = "Text_ID" + " " + '"' + array4[1];
        streamWriter.WriteLine(value);
    }
    else
    {
        streamWriter.WriteLine(text2);
    }
}

Answer 1

您可以使用File.ReadAllLines将文件读入数组，然后在数组中搜索要更改的行，用新字符串替换该行，然后使用File.WriteAllLines写入数组返回文件：

var filePath = @"f:\public\temp\temp.txt";

// The string to search for
var searchTxt = "Text_ID";

// Read all the lines of the file into an array
var fileLines = File.ReadAllLines(filePath);

// Loop through each line in the array
for(int i = 0; i < fileLines.Length; i++)
{
    // Check if the line begins with our search term
    if (fileLines[i].Trim().StartsWith(searchTxt, StringComparison.OrdinalIgnoreCase))
    {
        // Get the end of the line, after the last underscore
        var lastPartOfLine = fileLines[i].Substring(fileLines[i].LastIndexOf("_") + 1);

        // Combine our search string, a quote, and the end of the line
        fileLines[i] = $"{searchTxt} \"{lastPartOfLine}";

        // We found what we were looking for, so we can exit the for loop now
        // Remove this line if you expect to find more than one match
        break;
    }
}

// Write the lines back to the file
File.WriteAllLines(filePath, fileLines);

如果您只想保存文件的最后四行，可以调用Skip并传入数组的Length减去要保留的行数。这会跳过您要保存的所有条目：

// Read all the lines of the file into an array
var fileLines = File.ReadAllLines(filePath);

// Take only the last 4 lines
fileLines = fileLines.Skip(fileLines.Length - 4).ToArray();

Answer 2

尝试下面的代码，希望它适合你。

 var startsWith = "Text_ID";

 var allLines = File.ReadAllLines("a.txt").ToList();
 allLines = allLines.Select(ln =>
 {
     if(ln.StartsWith(startsWith))
     {
         var finalValue = ln.Split(' ')[1].Trim('"').Split('_').Last();
         //get update line
         return string.Format("{0} \"{1}\"", startsWith, finalValue);
     }
     return ln;
 }).ToList();

 //Write back to file.
 File.WriteAllLines("a.txt", allLines.ToArray());

代码执行前的内容。

Record 1
Text_ID "441124_aad0656_1234"
other content.
Record 2
Text_ID "Deepak_Sharma"
other content for line 2

执行后的文件内容。

Record 1
Text_ID "1234"
other content.
Record 2
Text_ID "Sharma"
other content for line 2

更改字符串“Text_ID”旁边的文件夹中的文本中的文本

2 个答案: