Null character
control character whose bits are all 0
The null character is a control character with the value zero. Many character sets include a code point for a null character – including Unicode (Universal Coded Character Set), ASCII (ISO/IEC 646), Baudot, ITA2 codes, the C0 control code, and EBCDIC. In modern character sets, the null character has a code point value of zero which is generally translated to a single code unit with a zero value. For instance, in UTF-8, it is a single, zero byte.
Originally, its meaning was like NOP – when sent to a printer or a terminal, it had no effect (although some terminals incorrectly displayed it as space). When electromechanical teleprinters were used as computer output devices, one or more null characters were sent at the end of each printed line to allow time for the mechanism to return to the first printing position on the next line. On punched tape, the character is represented with no holes at all, so a new unpunched tape is initially filled with null characters, and often text could be inserted at a reserved space of null characters by punching the new characters into the tape over the nulls.
A null-terminated string is a commonly used data structure in the C programming language, its many derivative languages and other programming contexts that uses a null character to indicate the end of a string.
This design allows a string to be any length at the cost of only one extra character of memory. The common competing design for a string stores the length of the string as an integer data type, but this limits the size of the string to the range of the integer (for example, 255 for a byte).
For byte storage, the null character can be called a null byte.
Begin with the source’s own compact description: “Null character” is control character whose bits are all 0. The dossier treats that line as a proposition to test through Null, character and control, not as a finished interpretation.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Jun 30, 2026. The linked authority identifier is Q861529. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Null character” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.