ASCII·_
95
_
0x5F · 1011111

ASCII 95 — the _ character

Punctuation

_ is 95 in decimal, 5F in hex and 1011111 in binary.

The marks scattered between the digits and the letters.

Seven bits

ASCII is seven bits wide, which is why there are 128 of them. The eighth bit was long left for parity.

1011111

One bit — the sixth, worth 32 — separates the cases. Off gives a capital, on gives a lowercase letter.

Kind
Punctuation
Decimal
95
Hexadecimal
0x5F
Octal
137
Binary
1011111
HTML entity
_
URL encoding
_
CSS escape
\5F

The chart

Eight columns for the top three bits, sixteen rows for the bottom four. The capitals column sits right beside the lowercase one — that is the shape of the table.

Codes either side

How to read this

  • Add 32 to a capital and you get the lowercase letter — one bit flips.
  • Digits start at 48, so subtracting 48 from the code gives the number.
  • Holding Ctrl clears the top three bits — that is why Ctrl+I is a tab.
  • Everything under 32, plus 127, draws nothing. Those show their abbreviation instead.

Frequently asked questions

Q. What is the ASCII code for _?

Decimal 95, hex 5F, octal 137, binary 1011111.

Q. How do I write _ in HTML?

As _.

Q. How does it go in a URL?

It can stay as it is — this character needs no encoding.

Q. Does _ have a partner?

No case partner: it is not a letter but a symbol.