Streamwriter 不会覆盖文件，保持追加或仅写入第一行

Question

Been looking through other people's answers and nothing seems to work.

Here is my code:

    public void TaskOnClick() //getting multi-values
    {
        foreach (string inputJson in File.ReadLines("Assets/Text/multi-import.txt"))
        {
            string temperature = GetTemperatureByRegex(inputJson);
            Debug.Log(temperature);

            string filename = "Assets/Text/TEMP/multi-export.txt";
            {
                using (StreamWriter writeFile = new StreamWriter(filename, false))
                {
                    writeFile.AutoFlush = true;
                    Console.SetOut(writeFile);
                    writeFile.WriteLineAsync(temperature.ToString());
                }
            }
        }

    }

The idea is that my parsing script gets my data and then streamwriter writes the data to a txt file. Problem is that streamwriter keeps appending the txt file instead of overwriting the file. Whenever I try to use filestream it overwrites the file, yes, but only the first line of the data gets written, no matter what I tried.

My username speaks for itself...

Answer 1

Why don't you just delete the file before opening the stream writer?

if(File.Exists(filename)){
             File.Delete(filename);
             }
   //here whatever you need to do next

Answer 2

What you do wrong is creating StreamWriter inside a loop. If you provide an overwrite settings it will only write 1 line.

public void TaskOnClick() //getting multi-values
    {
       string filename = "Assets/Text/TEMP/multi-export.txt";
       using (StreamWriter writeFile = new StreamWriter(filename, false))
       {
        foreach (string inputJson in File.ReadLines("Assets/Text/multi-import.txt"))
        {
            string temperature = GetTemperatureByRegex(inputJson);
            Debug.Log(temperature);  
            writeFile.AutoFlush = true;
            Console.SetOut(writeFile);
            writeFile.WriteLine(temperature.ToString());            
        }
      }
    }

But there is a shorter way of doing this with the help of LINQ.

public void TaskOnClick() //getting multi-values
    {
       string filename = "Assets/Text/TEMP/multi-export.txt";            
       var tempratures = File.ReadAllLines("Assets/Text/multi-import.txt")
                         .Select(GetTemperatureByRegex).ToArray();
       File.WriteAllLines(filename,tempratures); // it creates a new file or overwrites

     }    

I have to state that above method may be dangerous if input file is too large. Because it reads entire file into memory.