0xDEADBEEF

0xDEADBEEF is a hexadecimal constant widely used in computing as a recognizable marker or test value. Interpreted as an unsigned 32-bit integer, it equals 3735928559; if treated as signed 32-bit, it would be -559038737. The value is not defined by any standard but has become part of programming folklore due to its memorable spelling.

Usage and purpose

The pattern is commonly employed in example code, debugging, and memory initialization to reveal data patterns, sentinel conditions, or invalid pointers. It serves as a conspicuous placeholder that is unlikely to appear in normal data, helping developers quickly identify when a region of memory or a variable contains the marker rather than legitimate content. It is not tied to a specific operation and is chosen for readability and ease of recognition.

Memory and endianness

In memory, the byte order of 0xDEADBEEF depends on the architecture. On big-endian systems, the bytes appear as DE AD BE EF. On little-endian systems, they appear as EF BE AD DE. This endianness detail is relevant when diagnosing memory contents in low-level debugging.

Related patterns

0xDEADBEEF is part of a broader family of hex “magic numbers” used for debugging, alongside examples such as 0xBAADF00D, 0xCAFEBABE, and 0xFEEDFACE. These values share the goal of being easily identifiable and unlikely to occur accidentally in normal data.