0xff

0xFF is a hexadecimal literal used in computing to denote the value 255 in decimal. The prefix 0x signals hexadecimal notation, and FF are the two hexadecimal digits that together represent eight bits all set to 1. In binary this value is 11111111.

As an eight-bit value, 0xFF is the maximum unsigned byte value. In a signed eight-bit interpretation using two’s complement, 0xFF corresponds to -1. In many programming languages, the literal 0xFF is an integer constant with the value 255, and its interpretation can depend on how it is cast or stored in a particular type.

0xFF is commonly used as a byte mask and as a way to extract or manipulate full-byte data. For example, applying a bitwise AND with 0xFF can isolate the least significant byte of a larger integer. It is also used to set all bits in a byte, such as turning on all flags in a bit field.

In color representation, 0xFF commonly appears in 8-bit-per-channel color systems. Each of the red, green, and blue channels ranges from 0 to 255, so a value of 0xFF indicates full intensity for that channel. A color like 0xFF0000 represents pure red, and 0xFFFFFF represents white.

In networking, 0xFF is associated with broadcast addressing in IPv4, where 255.255.255.255 uses the maximum byte value for all octets. Some binary file formats also use 0xFF as marker or padding values; for example, JPEG streams use 0xFF as a marker prefix in the file structure.

Overall, 0xFF is a compact way to express the concept of “all ones” in a byte and serves as a widely used maximum value and mask in various technical contexts.