How does the pointer in C work in this algorithm?

Question

I have a program to calculate the highest value of consonants in a string as followed:

int solve(const char* strin) {
  char *vowels = "aeiou";
  int solution = 0;
  int current = 0;
  char *c;
  while(c = *strin++) {
    current = strchr(vowels, c) ? 0 : current + c - 96;
    if(current > solution) solution = current;
  }
  return solution;
}

I got quite confused with the command char *vowels = "aeiou"; because, as I've learned at university, the pointer only refers to the first element in an array unless there exists an increment or decrement. Is it valid to write like this? And why?

Answer 1

When you write

char* vowels = "aeiou";

the pointer vowels points to the first element of the "array" ie 'a', what you do with that pointer is up to you, if you eg want access the third element that vowels points to then *(vowels + 2) will give you that - the address of the same is vowels + 2

you can also declare vowels like this

char vowels[] = "aeiou";  here vowels again tells where the array starts

the prototype of strchr looks like this

char *strchr( const char *str, int ch );

When you pass in vowels you tell the function to start looking where vowels starts for the 'ch'. strchr looks until it finds the end of the string which is a \\0 , if it finds it returns a pointer to that location ie vowels + 0, +1 ,...