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These changes are to improve the experience for publishing these proposals. One change should be carefully reviewed to ensure I didn't introduce any technical errors: I translated the binary literals grammar into ANTLR to match all other specs and proposals. See changes in proposals/csharp-7.0/binary-literals.md Other changes are: 1. Use consistent ATX headers, with one H1 per proposal. 1. use `csharp` as language identifier in code snippets 1. Use relative links to other markdown from the dotnet/csharplang repo. That way, when published on docs.microsoft.com, the links will resolve to the publsihed articles on the same site. (Links to content not being published are not modified.) 1. spelling / capitalization found by the lint tool.
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Binary literals
There’s a relatively common request to add binary literals to C# and VB. For bitmasks (e.g. flag enums) this seems genuinely useful, but it would also be great just for educational purposes.
Binary literals would look like this:
int nineteen = 0b10011;
Syntactically and semantically they are identical to hexadecimal literals, except for using b/B instead of x/X, having only digits 0 and 1 and being interpreted in base 2 instead of 16.
There’s little cost to implementing these, and little conceptual overhead to users of the language.
Syntax
The grammar would be as follows:
integer-literal:
: ...
| binary-integer-literal
;
binary-integer-literal:
: `0b` binary-digits integer-type-suffix-opt
| `0B` binary-digits integer-type-suffix-opt
;
binary-digits:
: binary-digit
| binary-digits binary-digit
;
binary-digit:
: `0`
| `1`
;