iterate char** why does this work?

Question

I picked up a this piece of code I copy past to my program. This seems to be a new way to me to iterate through char**:

char** vArray;          // The array containing values

// Go throught properties
if(szKey == "KeyMgmt")
{
    vArray = (char**)g_value_get_boxed((GValue*)value);
    for( ; vArray && *vArray ; vArray++)  // Why does this work ?!
        pWpaKey->addKeyMgmt(std::string(*vArray));
}
else if(szKey == "Pairwise")
{
    // ...
}

It looks like to work like a charm but I don't understant why! vArray is Supposed to contain an adress right? And *vArray the "string" value. So why when I "AND" an address with its value this give me an equality?

Answer 1

vArray && *vArray is equivalent to (vArray != NULL) && (*vArray != NULL)

It's first checking that the pointer vArray isn't NULL and, assuming it is not NULL , checking that the pointer it points to isn't NULL .

Answer 2

The loop condition is

vArray && *vArray

This is basically shorthand for

(vArray != 0) && (*vArray != 0)

which is true if the char** pointer is non-null and points to a char* which is non-null.