Binary literal is an integer whose value is represented in the source code using the binary number system. Binary literals are a feature supported in many programming languages such as Java, D and Python as well as in a compiler extension in C++ and C. Binary literals typically start with 0b or 0B followed by a series of binary digits.

Java

Starting with Java 7, binary literals are possible to be expressed using the 0b or 0B prefix. For example:

//an octet value
byte b = (byte)0b00010101;

//a 32-bit integer value
int i = 0b001101010110101010001111011101;
int i2 = 0b1110;

Python

Starting with Python 2.6, binary literals support was added via the "0b" and "0B" prefixes.

Lisp

Lisp supports binary literals to represent integers and rational values via the #b prefix, for example:

#b10111

; rational values
#b1110/1111

C++ and C

Binary literals already exist in the C++ and C languages in the form of non-standard compiler extensions. They are prefixed with 0b or 0B followed by a series or binary digits. Binary literals have also been proposed as a core language addition in C++14.