Question

I have this code:

int indexOf(const char *array[], char *e)
{
     printf("inside: %d\n",(int)sizeof(array));
/* ... */
}

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

    const char *a[] = {";", ",", ":", "==", ":="};
    char *b = "==";
    printf("outside: %d\n",(int)sizeof(a));
    int d = indexOf(a,b);
/* ... */
}

And this is the output:

outside: 40
inside: 8

Why output is not the same? Any help, please?

Answer 1

The array decays into a pointer to it’s first element when passed to a function. The sizeof from the function yields the size of the pointer on your implementation. You could have declared it:

int indexOf(const char **array, char *e)

You will probably want to pass the length as a separate parameter.

EDIT

What I’m trying is to avoid to pass the size as a parameter.

In that case you could mark the end of the array with a NULL

const char *a[] = {";", ",", ":", "==", ":=", NULL};

That way in the function you will know where it ends.