Literal expressions
A literal expression is an expression consisting of a single token, rather than a sequence of
tokens, that immediately and directly denotes the value it evaluates to, rather than referring to it
by name or some other evaluation rule.
The supported literal expressions are described next.
Numeric literals
Cairo supports the following numeric literals:
1. A decimal literal that consists of only decimal digits.
2. A hexadecimal literal that start with the character sequence 0x and continues with hex digits.
3. A binary literal that start with the character sequence 0b and continues with binary digits.
A numeric literal may be followed (immediately, without any spaces) by an underscore character (_)
and then a literal suffix, which forcibly sets the type of the literal.
The literal suffix is any valid identifier, but only selected values are semantically correct.
|
Floating-point numbers are not supported. |
Examples of numeric literals of various forms:
| Literal | Value | Type |
|---|---|---|
|
1234 |
|
`1234_felt252 |
1234 |
|
`1234_u32 |
1234 |
|
`1234_u128 |
1234 |
|
|
1234 |
|
|
1234 |
|
Examples of invalid numeric literals:
-
Invalid suffix:
1234suffix -
Use of digits of wrong base:
123AFB43,0b0102,0o0581,0xG. -
Binary and hexadecimal literals must have at least one digit:
0b,0x_u128
|
Cairo syntax considers |
Short string literals
A short string is a ascii-string whose length is limited by the type that holds it.
The default type is a felt252 which limits the length of the string to 31 characters.
A short string literal may be followed by an underscore character (_)
and then a literal suffix just like a numerical literal.
Examples of short string literals:
-
'short_string' -
'short_string'_u128 -
'a'_u8
Note that a short-string is a way to encode a string as a numerical value, it is not a string type. Cairo doesn’t have a string type at the moment.
The short string’s first character is the most significant byte of the integer (big endian representation).