Efficient detection of string encoding in C#

Accurate judgment of string encoding is crucial for processing text data from different sources. This article will explore how to achieve this goal efficiently in C#.

Coding clues

There are several ways to determine the encoding of a string without explicit declaration:

1. BOM (byte order mark): Many Unicode encodings contain three-byte or four-byte signatures at the beginning of a file to indicate their encoding. For example, UTF-8 uses 0xEFBBBF.
2. Probe/Heuristic Check: By checking the first few bytes of a string, we can try to detect the encoding. For example, UTF-8 tends to have a byte pattern where a specific high bit is set.
3. Metadata in File: Some files embed encoded information in their content or metadata. Find patterns in text such as "charset=xyz" or "encoding=xyz".

Solution Overview

combines all three methods to determine the encoding of a string, first of which is BOM detection. If the BOM is not found, the code uses a detector to heuristically identify common encodings such as UTF-8 and UTF-16. Finally, if no suitable encoding is found, it will fall back to the system's default code page.

This code not only detects encoding, but also returns the decoded text to provide the required information in full.

Code implementation

The following C# code implements this solution:

public Encoding detectTextEncoding(string filename, out String text, int taster = 1000)
{
    // 检查BOM
    // 为简洁起见省略

    // 基于探测器的编码检测
    bool utf8 = false;
    int i = 0;
    while (i 

Usage method

To use this code, provide the file path as the string and retrieve the detected encoded and decoded text as the output parameters. Here is an example:

All in all, this code provides a powerful way to determine the encoding of strings in C#, leveraging BOM and heuristic checks to ensure accurate detection.