Question

Through trial and error I managed to get the following string comparison function to work with qsort() as I intended but I don’t really understand why the asterisk is needed in the (const char*) cast expression. Can someone please dissect and explain:-

int strCompare(const void *a, const void *b) {
    return strcmp((const char*)a, (const char*)b);
} 

Appendix:-

void findStrings(int * optionStats, char strings[][MAX_STRING_SIZE + 1], int numStrings)
{
    qsort(strings, numStrings, 21*sizeof(char), strCompare);
}

Is there a way of eliminating the call to strcmp() through strCompare() and just using strcmp() as the parameter to qsort() instead?

Answer 1

You need an asterisk because you want to convert a pointer to const void to a pointer to const char and an asterisk designates that they are pointer types.

In fact you don’t really need conversion, since pointer to void type can be implicitly converted to pointer to T type in C language, which isn’t the case for C++.