0x03

0x03 is the hexadecimal notation for the integer value 3. In most programming languages, the prefix 0x indicates a base-16 number, so 0x03 equals the decimal 3. In binary, it is represented as 00000011 in an 8-bit form.

In ASCII and Unicode, the code point U+0003 corresponds to the End of Text (ETX) control character. ETX is non-printable and was historically used to signal the end of a text transmission in early communication protocols rather than to represent a visible character.

Applications and usage

As a bitmask or flag, 0x03 represents the two least significant bits set (bits 0 and 1). It is common in programming to use 0x03 in bitwise operations, such as masking or testing those bits. For example, (value & 0x03) tests whether both of the lowest two bits are 1, while value | 0x03 would set them and value & ~0x03 would clear them.

Other contexts

In some binary protocols or file formats, 0x03 may appear as a type indicator or length field, but its meaning is specific to the given specification. In source code, a byte with value 0x03 can be stored in an integer variable or embedded in a string using a sequence like \x03, which inserts the ETX control character into the data.

Notes

Because 0x03 is a non-printable control character in ASCII, it typically does not produce a visible glyph when displayed and may be shown as a placeholder or suppressed by terminals and editors.