Question

I couldn’t understand what does the operator “<<” means in the following code.

    long hashString(char* key)
 {
   int n = strlen(key);
   long h = 0;
   for(int i=0; i<n; i++)
     {
        h = (h << 2) + key[i];
     }
  return abs(h % tablesize);
 }

Answer 1

It’s the left shift operator. It shifts the value left by 2 bits, effectively multiplying it with 2 to the power of 2 (the shift amount).

a << b

Is the same as:

a * (2 to the power of b)