public static bool IsPlainText(string fileName)
{
var fileInfo = new FileInfo(fileName);
if (fileInfo.Length < 20)
{
return(false); // too short to be plain text
}
if (fileInfo.Length > 5000000)
{
return(false); // too large to be plain text
}
var enc = LanguageAutoDetect.GetEncodingFromFile(fileName);
var s = File.ReadAllText(fileName, enc);
int numberCount = 0;
int letterCount = 0;
int len = s.Length;
for (int i = 0; i < len; i++)
{
char ch = s[i];
if (char.IsLetter(ch) || " -,.!?[]()\r\n".Contains(ch))
{
letterCount++;
}
else if (char.IsControl(ch) && ch != '\t') // binary found
{
return(false);
}
else if (CharUtils.IsDigit(ch))
{
numberCount++;
}
}
if (len < 100)
{
return(numberCount < 5 && letterCount > 20);
}
var numberThreshold = len * 0.002 + 1;
var letterThreshold = len * 0.8;
return(numberCount < numberThreshold && letterCount > letterThreshold);
}
public static bool IsPlainText(string fileName)
{
var fileInfo = new FileInfo(fileName);
if (fileInfo.Length < 20)
{
return(false); // too short to be plain text
}
if (fileInfo.Length > 5000000)
{
return(false); // too large to be plain text
}
var enc = LanguageAutoDetect.GetEncodingFromFile(fileName);
var s = ReadAllTextShared(fileName, enc);
int numberCount = 0;
int letterCount = 0;
int len = s.Length;
for (int i = 0; i < len; i++)
{
var ch = s[i];
if (char.IsLetter(ch) || " -,.!?[]()\r\n".Contains(ch))
{
letterCount++;
}
else if (char.IsControl(ch) && ch != '\t') // binary found
{
return(false);
}
else if (CharUtils.IsDigit(ch))
{
numberCount++;
}
}
if (len < 100)
{
return(numberCount < 5 && letterCount > 20);
}
var numberPatternMatches = new Regex(@"\d+[.:,; -]\d+").Matches(s);
if (numberPatternMatches.Count > 30)
{
return(false); // looks like time codes
}
var largeBlocksOfLargeNumbers = new Regex(@"\d{3,8}").Matches(s);
if (largeBlocksOfLargeNumbers.Count > 30)
{
return(false); // looks like time codes
}
if (len < 1000 && largeBlocksOfLargeNumbers.Count > 10)
{
return(false); // looks like time codes
}
var partsWithMoreThan100CharsOfNonNumbers = new Regex(@"[^\d]{150,100000}").Matches(s);
if (partsWithMoreThan100CharsOfNonNumbers.Count > 10)
{
return(true); // looks like text
}
var numberThreshold = len * 0.015 + 25;
var letterThreshold = len * 0.8;
return(numberCount < numberThreshold && letterCount > letterThreshold);
}