Question

我的代码是

Dictionary<string,string> members = new Dictionary<string,string>();
//.. initialization of this dictionary

                using (StreamWriter file = new StreamWriter(pathToFile))
                    foreach (var entry in members)
                        file.WriteLine("[{0} {1}]", entry.Key, entry.Value);

我需要在文件“testString”中出现的第一个指定字符串之后编写这些内容。如何轻松完成？

Answer 1

您是否需要在中间插入数据（即引用：“在这个文件中可能出现的第一个指定字符串之后写这个东西”）？

Dictionary<string, string> members = new Dictionary<string, string>();

String lineToFind = "testString";

// Let's read the file up in order to avoid read/write conflicts
var data = File
  .ReadLines(pathToFile)
  .ToList();

var before = data
  .TakeWhile(line => line != lineToFind)
  .Concat(new String[] {lineToFind}); // add lineToFind

var after = data
  .SkipWhile(line => line != lineToFind)
  .Skip(1); // skip lineToFind

var stuff = members
  .Select(entry => String.Format("[{0} {1}]", entry.Key, entry.Value));

File.WriteAllLines(pathToFile, before
  .Concat(stuff)
  .Concat(after));

Answer 2

您可以从文件中读取所有内容并以字符串形式存储。然后找到指定子字符串的索引并插入新值。然后使用以下命令回写文本文件：

using (StreamWriter file = new StreamWriter(pathToFile, false)){}

Answer 3

创建一个临时文件并逐行写入所有数据，同时遍历所有行搜索指定的字符串并将数据插入到找到它的位置。同时尽量减少内存消耗。

Dictionary<string, string> members = new Dictionary<string, string>();
//.. initialization of this dictionary

string pathToFile = "";

string tempfile = Path.GetTempFileName();   //create a temp file
using (var writer = new StreamWriter(tempfile))
using (var reader = new StreamReader(pathToFile))
{
    //if file is not ended
    while (!reader.EndOfStream)
    {
        //get next line
        string line = reader.ReadLine();

        //write it to the "temp file"
        writer.WriteLine(line);

        //search in the line, if found, insert your data
        if (line.Contains("search what you need"))
        {
            foreach (var entry in members)
                writer.WriteLine("[{0} {1}]", entry.Key, entry.Value);
        }                    
    }
}

//overwrite the actual file with temp file
File.Copy(tempfile, pathToFile, true);

鸣谢：我在回答Jake时使用了here的逻辑。

在指定字符串后写入文本文件？

3 个答案: