출처2 : https://social.msdn.microsoft.com/Forums/ko-KR/b172cd4d-25fe-4696-8c0f-37226c053d71/how-to-detect-encoding-file-in-ansi-utf8-and-utf8-without-bom?forum=csharpgeneral

//인코딩 확인

public static Encoding GetFileEncoding(string srcFile)

{

// *** Use Default of Encoding.Default (Ansi CodePage)

Encoding enc = Encoding.Default;

// *** Detect byte order mark if any - otherwise assume default

byte[] buffer = new byte[10];

FileStream file = new FileStream(srcFile, FileMode.Open, FileAccess.Read, FileShare.Read);

file.Read(buffer, 0, 10);

file.Close();

if (buffer[0] == 0xef && buffer[1] == 0xbb && buffer[2] == 0xbf)

enc = Encoding.UTF8; //with BOM

else if (buffer[0] == 0xfe && buffer[1] == 0xff)

enc = Encoding.Unicode;

else if (buffer[0] == 0 && buffer[1] == 0 && buffer[2] == 0xfe && buffer[3] == 0xff)

enc = Encoding.UTF32;

else if (buffer[0] == 0x2b && buffer[1] == 0x2f && buffer[2] == 0x76)

enc = Encoding.UTF7;

else if (buffer[0] == 0xFE && buffer[1] == 0xFF)

// 1201 unicodeFFFE Unicode (Big-Endian)

enc = Encoding.GetEncoding(1201);

else if (buffer[0] == 0xFF && buffer[1] == 0xFE)

// 1200 utf-16 Unicode

enc = Encoding.GetEncoding(1200);

else if (ValidateUTF8WithoutBOM(srcFile))

enc = new UTF8Encoding(false);

return enc;

}

private static bool ValidateUTF8WithoutBOM(string filePath)

{

//ansi로 인코딩 된 파일을 utf-8을 사용하여 읽으면 각 기본 언어마다 특수문자가 포함되는 것같다.

//euc-kr 에서 utf-8로 읽으면 "� = (char)0xfffd)"가 생기는 것 같다.

using (FileStream fs = File.Open(filePath, FileMode.Open, FileAccess.Read))

using (BufferedStream bs = new BufferedStream(fs))

using (StreamReader sr = new StreamReader(bs))

{

if (fs.Length < 1024 * 1000)

{

if (sr.ReadToEnd().Contains((char)0xfffd))

return false;

else

return true;

}

string s;

while ((s = sr.ReadLine()) != null)

{

if (s.Contains((char)0xfffd))

return false;

}

}

return true;

}

//파일 읽기

public static string ReadText(string filePath)

{

StringBuilder sb = new StringBuilder();

using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))

{

using (StreamReader sr = new StreamReader(fs, GetFileEncoding(filePath), true))

{

string line;

while ((line = sr.ReadLine()) != null)

{

sb.AppendLine(line);

}

}

return sb.ToString();

}

}

//파일 쓰기

public static void WriteText(string filePath, string strData)

{

DirectoryInfo di = new DirectoryInfo(Path.GetDirectoryName(filePath));

if (di.Exists == false) //If New Folder not exits

{

di.Create(); //create Folder

}

using (FileStream fs = new FileStream(filePath, FileMode.Create, FileAccess.Write))

{

using (StreamWriter sw = new StreamWriter(fs, new UTF8Encoding(false)))

{

sw.WriteLine(strData.TrimEnd());

}

}

}

[C#] txt 파일 읽기, 쓰기 read line write line