ASCII 63
Question Mark (?)
Printable ASCII
Question mark. Ternary operator (a ? b : c), optional chaining (?.), URL query separator.
Common uses & context
The character '?' — Question Mark — has ASCII code 63 (0x3F), octal 0077, binary 00111111. Question mark. Ternary operator (a ? b : c), optional chaining (?.), URL query separator.
Punctuation and symbol codes carry the most syntactic weight per byte in programming: a single '?' can change how a parser reads an entire expression. When '?' needs to appear as literal data rather than syntax, you often have to escape it — in string literals, in regular expressions, in URLs (where it becomes %3F), or in HTML. Knowing its exact code point (63) helps when you filter, validate, or sanitize input byte by byte.
All encodings at a glance
| Decimal | 63 |
| Hexadecimal | 0x3F |
| Octal | 0077 |
| Binary | 00111111 |
| HTML numeric entity | ? |
| URL encoding | %3F |
| UTF-8 bytes | 0x3F |
Code snippets
JavaScript
String.fromCharCode(63); // "?"
63.toString(16); // "3f"Python
chr(63) # '?'
ord(chr(63)) # 63
hex(63) # '0x3f'HTML
? <!-- numeric entity (no named entity for this character) -->Programming notes
- ▸Code 63 (0x3F); URL-encoded form%3F.
- ▸In HTML the numeric entity is ?.
- ▸When used as literal data in regex or strings, '?' usually needs escaping — check the rules for your language.
Frequently asked questions
What character is ASCII code 63?
ASCII code 63 is the character '?' (Question Mark). In hexadecimal it is 0x3F, in octal 0077, and in binary 00111111.
What is 0x3F in ASCII?
Hexadecimal 0x3F equals decimal 63, which is the character '?' (Question Mark). To convert hex to ASCII yourself, read the two hex digits as a base-16 number (0x3F = 63) and look up that code point.
How do I write the character with code 63 in code?
In JavaScript use String.fromCharCode(63); in Python use chr(63); in HTML use the numeric entity ?. In a URL it is percent-encoded as %3F, and in UTF-8 it is stored as the byte sequence 0x3F.