नीचे दिए गए कोड में निम्नलिखित विशेषताएं हैं:
- UTF-7, UTF-8/16/32 का पता लगाने या प्रयास करने का पता लगाने (बम, कोई बम, छोटा और बड़ा एंडियन)
- यदि कोई यूनिकोड एन्कोडिंग नहीं मिला तो स्थानीय डिफ़ॉल्ट कोडपेज पर वापस आ जाता है।
- BOM / हस्ताक्षर गायब होने के साथ (उच्च संभावना के साथ) यूनिकोड फ़ाइलों का पता लगाता है
- एन्कोडिंग निर्धारित करने में मदद करने के लिए फ़ाइल के अंदर charset = xyz और एन्कोडिंग = xyz के लिए खोजें।
- प्रसंस्करण को बचाने के लिए, आप फ़ाइल (बाइट्स की निश्चित संख्या) का स्वाद ले सकते हैं।
- एन्कोडिंग और डीकोड की गई फ़ाइल वापस कर दी जाती है।
- विशुद्ध रूप से दक्षता के लिए बाइट-आधारित समाधान
जैसा कि अन्य लोगों ने कहा है, कोई भी समाधान सही नहीं हो सकता है (और निश्चित रूप से दुनिया भर में उपयोग किए जा रहे विभिन्न 8-बिट विस्तारित ASCII एन्कोडिंग में आसानी से अंतर नहीं किया जा सकता है), लेकिन हम विशेष रूप से 'अच्छा पर्याप्त' प्राप्त कर सकते हैं यदि डेवलपर भी उपयोगकर्ता को प्रस्तुत करता है यहाँ दिखाए गए अनुसार वैकल्पिक एनकोडिंग की एक सूची: प्रत्येक भाषा का सबसे आम एन्कोडिंग क्या है?
एन्कोडिंग की एक पूरी सूची का उपयोग करके पाया जा सकता है Encoding.GetEncodings();
// Function to detect the encoding for UTF-7, UTF-8/16/32 (bom, no bom, little
// & big endian), and local default codepage, and potentially other codepages.
// 'taster' = number of bytes to check of the file (to save processing). Higher
// value is slower, but more reliable (especially UTF-8 with special characters
// later on may appear to be ASCII initially). If taster = 0, then taster
// becomes the length of the file (for maximum reliability). 'text' is simply
// the string with the discovered encoding applied to the file.
public Encoding detectTextEncoding(string filename, out String text, int taster = 1000)
{
byte[] b = File.ReadAllBytes(filename);
//////////////// First check the low hanging fruit by checking if a
//////////////// BOM/signature exists (sourced from http://www.unicode.org/faq/utf_bom.html#bom4)
if (b.Length >= 4 && b[0] == 0x00 && b[1] == 0x00 && b[2] == 0xFE && b[3] == 0xFF) { text = Encoding.GetEncoding("utf-32BE").GetString(b, 4, b.Length - 4); return Encoding.GetEncoding("utf-32BE"); } // UTF-32, big-endian
else if (b.Length >= 4 && b[0] == 0xFF && b[1] == 0xFE && b[2] == 0x00 && b[3] == 0x00) { text = Encoding.UTF32.GetString(b, 4, b.Length - 4); return Encoding.UTF32; } // UTF-32, little-endian
else if (b.Length >= 2 && b[0] == 0xFE && b[1] == 0xFF) { text = Encoding.BigEndianUnicode.GetString(b, 2, b.Length - 2); return Encoding.BigEndianUnicode; } // UTF-16, big-endian
else if (b.Length >= 2 && b[0] == 0xFF && b[1] == 0xFE) { text = Encoding.Unicode.GetString(b, 2, b.Length - 2); return Encoding.Unicode; } // UTF-16, little-endian
else if (b.Length >= 3 && b[0] == 0xEF && b[1] == 0xBB && b[2] == 0xBF) { text = Encoding.UTF8.GetString(b, 3, b.Length - 3); return Encoding.UTF8; } // UTF-8
else if (b.Length >= 3 && b[0] == 0x2b && b[1] == 0x2f && b[2] == 0x76) { text = Encoding.UTF7.GetString(b,3,b.Length-3); return Encoding.UTF7; } // UTF-7
//////////// If the code reaches here, no BOM/signature was found, so now
//////////// we need to 'taste' the file to see if can manually discover
//////////// the encoding. A high taster value is desired for UTF-8
if (taster == 0 || taster > b.Length) taster = b.Length; // Taster size can't be bigger than the filesize obviously.
// Some text files are encoded in UTF8, but have no BOM/signature. Hence
// the below manually checks for a UTF8 pattern. This code is based off
// the top answer at: /programming/6555015/check-for-invalid-utf8
// For our purposes, an unnecessarily strict (and terser/slower)
// implementation is shown at: /programming/1031645/how-to-detect-utf-8-in-plain-c
// For the below, false positives should be exceedingly rare (and would
// be either slightly malformed UTF-8 (which would suit our purposes
// anyway) or 8-bit extended ASCII/UTF-16/32 at a vanishingly long shot).
int i = 0;
bool utf8 = false;
while (i < taster - 4)
{
if (b[i] <= 0x7F) { i += 1; continue; } // If all characters are below 0x80, then it is valid UTF8, but UTF8 is not 'required' (and therefore the text is more desirable to be treated as the default codepage of the computer). Hence, there's no "utf8 = true;" code unlike the next three checks.
if (b[i] >= 0xC2 && b[i] <= 0xDF && b[i + 1] >= 0x80 && b[i + 1] < 0xC0) { i += 2; utf8 = true; continue; }
if (b[i] >= 0xE0 && b[i] <= 0xF0 && b[i + 1] >= 0x80 && b[i + 1] < 0xC0 && b[i + 2] >= 0x80 && b[i + 2] < 0xC0) { i += 3; utf8 = true; continue; }
if (b[i] >= 0xF0 && b[i] <= 0xF4 && b[i + 1] >= 0x80 && b[i + 1] < 0xC0 && b[i + 2] >= 0x80 && b[i + 2] < 0xC0 && b[i + 3] >= 0x80 && b[i + 3] < 0xC0) { i += 4; utf8 = true; continue; }
utf8 = false; break;
}
if (utf8 == true) {
text = Encoding.UTF8.GetString(b);
return Encoding.UTF8;
}
// The next check is a heuristic attempt to detect UTF-16 without a BOM.
// We simply look for zeroes in odd or even byte places, and if a certain
// threshold is reached, the code is 'probably' UF-16.
double threshold = 0.1; // proportion of chars step 2 which must be zeroed to be diagnosed as utf-16. 0.1 = 10%
int count = 0;
for (int n = 0; n < taster; n += 2) if (b[n] == 0) count++;
if (((double)count) / taster > threshold) { text = Encoding.BigEndianUnicode.GetString(b); return Encoding.BigEndianUnicode; }
count = 0;
for (int n = 1; n < taster; n += 2) if (b[n] == 0) count++;
if (((double)count) / taster > threshold) { text = Encoding.Unicode.GetString(b); return Encoding.Unicode; } // (little-endian)
// Finally, a long shot - let's see if we can find "charset=xyz" or
// "encoding=xyz" to identify the encoding:
for (int n = 0; n < taster-9; n++)
{
if (
((b[n + 0] == 'c' || b[n + 0] == 'C') && (b[n + 1] == 'h' || b[n + 1] == 'H') && (b[n + 2] == 'a' || b[n + 2] == 'A') && (b[n + 3] == 'r' || b[n + 3] == 'R') && (b[n + 4] == 's' || b[n + 4] == 'S') && (b[n + 5] == 'e' || b[n + 5] == 'E') && (b[n + 6] == 't' || b[n + 6] == 'T') && (b[n + 7] == '=')) ||
((b[n + 0] == 'e' || b[n + 0] == 'E') && (b[n + 1] == 'n' || b[n + 1] == 'N') && (b[n + 2] == 'c' || b[n + 2] == 'C') && (b[n + 3] == 'o' || b[n + 3] == 'O') && (b[n + 4] == 'd' || b[n + 4] == 'D') && (b[n + 5] == 'i' || b[n + 5] == 'I') && (b[n + 6] == 'n' || b[n + 6] == 'N') && (b[n + 7] == 'g' || b[n + 7] == 'G') && (b[n + 8] == '='))
)
{
if (b[n + 0] == 'c' || b[n + 0] == 'C') n += 8; else n += 9;
if (b[n] == '"' || b[n] == '\'') n++;
int oldn = n;
while (n < taster && (b[n] == '_' || b[n] == '-' || (b[n] >= '0' && b[n] <= '9') || (b[n] >= 'a' && b[n] <= 'z') || (b[n] >= 'A' && b[n] <= 'Z')))
{ n++; }
byte[] nb = new byte[n-oldn];
Array.Copy(b, oldn, nb, 0, n-oldn);
try {
string internalEnc = Encoding.ASCII.GetString(nb);
text = Encoding.GetEncoding(internalEnc).GetString(b);
return Encoding.GetEncoding(internalEnc);
}
catch { break; } // If C# doesn't recognize the name of the encoding, break.
}
}
// If all else fails, the encoding is probably (though certainly not
// definitely) the user's local codepage! One might present to the user a
// list of alternative encodings as shown here: /programming/8509339/what-is-the-most-common-encoding-of-each-language
// A full list can be found using Encoding.GetEncodings();
text = Encoding.Default.GetString(b);
return Encoding.Default;
}
