Comments begin with a pair of forward slashes // and end with a new line:

// A comment line

A comment block begins with /* and ends with */:

A comment block

Version string

The first non-comment line of an OpenQASM program may optionally be OPENQASM M.m ; indicating a major version M and minor version m. More details on versioning and the release cycle for OpenQASM may be found here.

The minor version number, expressed as a decimal point after the major version number followed by a number, is optional. If not present, the minor version number is assumed to be zero.

Multiple occurrences of the version string (outside of comments) are not permitted, nor may it appear elsewhere than the first non-comment line.

Included files

The statement include "filename"; continues parsing filename as if the contents of the file were inserted at the location of the include statement. This statement can only be used at the global scope.

// First non-comment is a version string

include "stdgates.qasm";

// Rest of QASM program