关于16位小端有符号二进制文件中'v'和'K'字符含义的咨询

Hey there! The confusion here all boils down to how little-endian byte ordering works for your 16-bit signed integers—you were accidentally using big-endian logic when calculating the value, which is why your manual math didn't match the correct result. Let's break this down step by step:

Key Background: Little-Endian vs Big-Endian #

For 16-bit integers:

• Big-endian: Stores the high byte first, low byte second (the "intuitive" left-to-right order for human reading)
• Little-endian: Stores the low byte first, high byte second (this is what your file uses!)

Python's byte string representation will show printable ASCII characters as their literal form (like 'v' or 'K') instead of hex escapes, but they're still just regular bytes under the hood.

Let's Unpack Your Examples #

1. Byte string b'v\x1d' → Value 7542

• First, get the hex values of each byte:
  • 'v' is a printable ASCII character; its hex value is 0x76 (decimal 118)
  • \x1d is the hex escape for 0x1D (decimal 29)
• Since it's little-endian, we reverse the byte order to form the 16-bit integer:
  • High byte: 0x1D, Low byte: 0x76 → Combined as 0x1D76
• Convert to decimal: (0x1D * 256) + 0x76 = (29 * 256) + 118 = 7424 + 118 = 7542 (matches your correct result!)

2. Byte string b'K\x1d' → Value 7499

• Hex values of each byte:
  • 'K' is ASCII for 0x4B (decimal 75)
  • \x1d is still 0x1D (decimal 29)
• Little-endian order reversal:
  • High byte: 0x1D, Low byte: 0x4B → Combined as 0x1D4B
• Decimal conversion: (29 * 256) + 75 = 7424 + 75 = 7499 (again, matches your correct result!)

Why Your Initial Calculation Was Wrong #

You were treating the byte string as big-endian: combining 'v' (0x76) as the high byte and \x1d (0x1D) as the low byte, giving 0x761D (decimal 30237). But since your file uses little-endian, the byte order is flipped—this is the core of the confusion!

Quick Recap #

• 'v' and 'K' aren't special "meaningful" characters here—they're just Python's way of displaying printable ASCII bytes instead of hex escapes. Their actual values are 0x76 and 0x4B respectively.
• Always remember: little-endian = low byte first, so reverse the byte order when calculating manually to match the conversion result.

内容的提问来源于stack exchange，提问作者Neira