switch statement

scrabble_score.h

#ifndef SCRABBLE_SCORE_H
#define SCRABBLE_SCORE_H

unsigned int score(const char *word);

#endif

scrabble_score.c

#include "scrabble_score.h"
#include <ctype.h>
#include <stddef.h>

static unsigned int letter_score(char letter)
{
   switch (tolower(letter)) {
      case 'a':
      case 'e':
      case 'i':
      case 'o':
      case 'u':
      case 'l':
      case 'n':
      case 'r':
      case 's':
      case 't':
         return 1;
      case 'd':
      case 'g':
         return 2;
      case 'b':
      case 'c':
      case 'm':
      case 'p':
         return 3;
      case 'f':
      case 'h':
      case 'v':
      case 'w':
      case 'y':
         return 4;
      case 'k':
         return 5;
      case 'j':
      case 'x':
         return 8;
      case 'q':
      case 'z':
         return 10;
   }
   return 0;
}

unsigned int score(const char *word)
{
   if (word == NULL)
      return 0;
   unsigned int total_score = 0;
   for (; *word; ++word)
      total_score += letter_score(*word);
   return total_score;
}

This approach starts by defining a function which takes a char. The tolower function is used on the input char passed to the switch.

Note that multiple values can be tested without putting a break statement between them. Also note that a break statement is not needed after a return statement.

The score function takes a pointer to the word being scored. It checks if the pointer is NULL. If so, then the function returns 0.

The variable to keep track of the accumulated score is initialized to 0.

The for loop begins with no initialization statement. The reason the total_score variable is not initialized in the for loop is because its scope would be confined to the loop and it would be destroyed at the end of the loop.

The conditional statement will iterate the loop as long as the word pointer is not pointing to a null character ('\0'). The loop increments the word pointer. Since the word pointer is being incremented directly, there is no counter variable needed to be defined and incremented.

Inside the loop, the character at the dereferenced pointer is sent to the letter_score function. The total_score variable is added to from the result of calling the letter_score function.

The loop will stop when the word pointer is pointing at a null character.

The value of the total_score variable is returned.