Defining an array inside a function argument in C

Question

Is there a way to define an array inside a function argument in C? Something like this:

void arraysomething(double vec[2]){
    //do something...
}

int main(){
    arraysomething({1.,2.});
    return 0;
}

I searched all over the place and found nothing.

C is a distinct language from C++. If the question is about C, the C++ tag is not appropriate. — François Andrieux
– François Andrieux, Commented Jun 11, 2018 at 19:12

dbush · Accepted Answer · 2018-06-11 19:19:29Z

5

What you're looking for is called a compound literal:

arraysomething((double []){1.,2.});

The syntax looks like an initializer for an array or struct preceeded by what looks like a cast to the type in question.

Because you want to pass in array, the typename given should be double [], which means an array of unspecified size. The actual size isn't needed because it is inferred from the number of elements in the literal.

edited Jun 11, 2018 at 19:19

answered Jun 11, 2018 at 19:12

dbush

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3 Comments

João Paulo Andrade Over a year ago

i got this message: stokes.c: In function 'main': stokes.c:312:30: warning: excess elements in scalar initializer dotproduct2(A, (double){1.,2.}); ^~ stokes.c:312:30: note: (near initialization for '(anonymous)') stokes.c:312:18: error: incompatible type for argument 2 of 'dotproduct2' dotproduct2(A, (double){1.,2.}); ^ stokes.c:45:8: note: expected 'double *' but argument is of type 'double' double dotproduct2(double A[2], double B[2]){

dbush Over a year ago

@JoãoPauloAndrade I made an edit. It should be (double []), not (double).

dbush Over a year ago

@JoãoPauloAndrade Glad I could help. Feel free to accept this answer if you found it useful.

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