Abdu's Garden

Little & Big Endian (Bidirectional & Monodirectional encoding)

2 min read

Big Endian and Little Endian (According to a ChatGPT answer)

In computing, the terms “Big Endian” and “Little Endian” refer to the byte order in which multi-byte data types, like integers and floating-point numbers, are stored in memory.

  • Big Endian: The most significant byte (MSB) is stored at the lowest memory address. In other words, the big end comes first.
  • Little Endian: The least significant byte (LSB) is stored at the lowest memory address. In other words, the little end comes first.

For example, consider the 32-bit (4 byte) hexadecimal number 0x12345678.

  • In Big Endian, it would be stored in memory as:

    12 34 56 78

  • In Little Endian, it would be stored in memory as:

    78 56 34 12

Different computer architectures use different endian-ness. For example, x86 and x86-64 architectures are little endian, while many older architectures like Motorola’s 68k were big endian. Some architectures are bi-endian, meaning they can operate in either mode.

Char Strings vs. Numbers

Character strings are sequences of individual bytes, and each byte in a character string represents a single character (in ASCII encoding, for example). When you access a string, you’re often treating each byte or character independently, so the overall byte order of the system doesn’t come into play the same way it does with multi-byte numerical values.

For example, the string “HELLO” in ASCII is represented as:

48 45 4C 4C 4F

Whether you’re on a big endian or little endian system, you’d still interpret this string the same way, from the first byte to the last.

However, for multi-byte numerical values, the order in which the bytes are read and interpreted is critical. If a 4-byte integer is read in the wrong byte order, it will represent a completely different value.

To summarize:

  • Char strings are sequences of individual characters, and the order of characters matters for human interpretation. Byte order within each character doesn’t matter because each character is typically a single byte.

  • Numbers that span multiple bytes have a specific value based on the combination of those bytes, so the order in which those bytes are combined matters a lot. Reading them in the wrong order will yield an incorrect numerical value.

Graph View