Why can't I pass constant arrays as arguments?

Solution 1:

Short answer: You need to make use of a compound literal. Something like

 arrayfn( (double[]) {1.0, 2.0, 3.0} );

should do the job.

Some explanation

Coming to the part, why arrayfn({1.0, 2.0, 3.0}); did not work, because, without the syntax for compound literals, {1.0, 2.0, 3.0} is a brace enclosed initializer list. It does not denote an "object" which can be used as function argument. They are not "constant arrays", as you may have thought.

To add some more info, quoting C11, chapter §6.5.2.5, Compound literals

A postfix expression that consists of a parenthesized type name followed by a brace-enclosed list of initializers is a compound literal. It provides an unnamed object whose value is given by the initializer list.