Question

In a book I am reading there is a piece of code :

string x;
size_t h=0;
for(const char* s=x.c_str();*s;++s)
    h=(h*17)^*s;

Regarding this code, I have two questions:

1. how can *s be a condition? what does it mean?

2. what does "h=(h*17)^*s" mean?

Thanks for help!

Answer 1

1. how can *s be a condition? what does it mean?

It means “while the value pointed to by s is not zero.” C strings are null-terminated, so the last character in the string returned by c_str() will be the null character (\0, represented by all bits zero).

2. what does “h=(h*17)^*s” mean?

It multiplies h by 17 then xors it with the value pointed to by s.