ASCII·\
92
\
0x5C · 1011100

ASCII 92 — the \ character

Punctuation

\ is 92 in decimal, 5C in hex and 1011100 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.

1011100

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

Kind
Punctuation
Decimal
92
Hexadecimal
0x5C
Octal
134
Binary
1011100
HTML entity
\
URL encoding
%5C
CSS escape
\5C
Short escape
\\

Only \e is missing from standard C; GCC, shells and regex engines take it.

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 92, hex 5C, octal 134, binary 1011100.

Q. How do I write \ in HTML?

As \.

Q. How does it go in a URL?

It is encoded as %5C.

Q. Does \ have a partner?

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