Question

I have code which does the following :

const char* filename = argc >= 2 ? argv[1] : "stuff.jpg";

which reads in a photo as a command line argument and displays it.

I now want to take in two photo’s, I tried this code :

const char* filename = argc >= 3 ? argv[1] : "stuff.jpg", argv[2] : "tester.jpg";

But I get an error like this :

error: expected initializer before ‘:’ token

Anybody know whats wrong? is there a similer way to do this input programmatically?

Answer 1

You’re dealing with a ternary if-operator here. Have a look at this page. It’s basically an inline if-statement.

Code that would do what you’re looking for, looks something a little like this:

const char* filename1 = argc >= 2 ? argv[1] : "stuff.jpg";
const char* filename2 = argc >= 3 ? argv[2] : "tester.jpg";

That leaves you with two filename variables, storing either the supplied argument or the default values (stuff.jpg and tester.jpg, respectively).