Question

Here I wrote a little app which is able to read command line arguments

int main (int argc, const char * argv[])
{
    int c;

    while ((c = getopt (argc, argv, "Il:o:vh?")) != -1) 
    {
        switch(c)
        {
            case 'I':
                printf("I");
                break;
        }
    }

    return 0;   
}

The problem is that when I try to compile it the compiler prints

warning: passing argument 2 of ‘getopt’ from incompatible pointer type

and program crash.
What I miss ?

Answer 1

The argv argument to main should have type char *[], not const char *[] so that it can be converted to the char *const [] that getopt expects. In fact, char *[] or equivalent is mandated by the C standard for hosted implementations.