pset5 check function error using tolower with const char*

Question

Below, I want to turn each letter in the array of word into lower case. I'm using a loop and tolower to change each letter. But I get this error when I compile:

dictionary.c:44:33: error: read-only variable is not assignable word[i] = tolower(word[i]);

Per the pset instructions, I can't change the type of word. Thoughts?

bool check(const char* word)
        {

            // Hash the word
            int index = 0;
            if(word[0] == '\'')
            {
                index = HASHLENGTH;
            }
            else
            {
                index = (tolower(word[0]) - 'a') % HASHLENGTH;
            }    

            // Initialize the return value    
            bool result = false;

            for(node* cur = HASHTABLE[index]; cur != NULL; cur = cur->next)
            {
                // turn to lower case
                for(int i = 0; i < strlen(word); i++)
                {
                    word[i] = tolower(word[i]);
                }


                if(strcmp(cur->word, word) == 0)
                {
                    result = true;
                    break;
                }        
            }

            return result;
        }

Answer 1

Easy solution. The key here is that word is fixed as a constant in bool check(const char* word). That means that it cannot be changed, period. However, there's nothing preventing you from copying the contents of word into another local string variable and altering, comparing, or otherwise operating on it.

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