CODEWITHSUNDEEP
creturnbooleanprintfconditional-statements
PYB
PYB

Reputation: 533

Bool function returns true without meeting condition - ignores printf()

I've been working 5 days straight on this program, and can't figure out why it's acting like this. Thanks for helping me out.

There is code in the file speller.c that calls 4 functions in the file dictionary.c
In speller.c, it calls a certain function:

bool misspelled = !check(word);

If misspelled is false, it means the check function returned true.

Here is the check function, in dictionary.c:

bool check(const char *word)
{
    int key = hash(word);
    printf("Word: %s    position: %i\n", word, key);
    node* trav = dictArray[key];

    while (trav != NULL)
    {
        if(trav->word == word)
            printf("%s found in the dictionary\n", word);
            return true;
        trav = trav->next;
    }
    printf("%s NOT found in the dictionary\n", word);
    return false;

Check() will go check in a hash table if it can find the word passed as argument in a hash table, and prints each word and it's key. If it finds it, it prints a message and return true. If not, prints a message saying so, and return false. The hash table is an array of 26 elements, each are a struct with 2 elements, one being a string, the other a pointer to the next struct (node) in the list. Nodes are added to lists depending on the first letter of the word.

The problem is that I have tested every word that gets added to the array, and even when the word is not there, the function still returns true. In fact, it returns true for every word passed as argument.

Now the really puzzling behavior is that check() has to print something to the screen, just before returning either true or false. Either ...found ... or ... NOT found .... Well it doesn't. But it still returns 'true', which confuses me.

Any help? Should I paste the whole code from both file?

Upvotes: 0

Views: 630

Answers (2)

dbush
dbush

Reputation: 223972

Look closely:

while (trav != NULL)
{
    if(trav->word == word)
        printf("%s found in the dictionary\n", word);
        return true;
    trav = trav->next;
}

There are no curly braces around the if block. So with proper indentation what you really have is:

while (trav != NULL)
{
    if(trav->word == word)
        printf("%s found in the dictionary\n", word);
    return true;
    trav = trav->next;
}

So you always return true on the first loop iteration.

Also, you don't want to use == to compare strings. What you end up doing is comparing the pointer values, which will almost always be not equal. Use strcmp to compare strings instead.

The fixed code:

while (trav != NULL)
{
    if(!strcmp(trav->word, word)) {
        printf("%s found in the dictionary\n", word);
        return true;
    }
    trav = trav->next;
}

Upvotes: 4

Carl Norum
Carl Norum

Reputation: 224944

This code block:

    if(trav->word == word)
        printf("%s found in the dictionary\n", word);
        return true;

Doesn't do what you think it does - add {} around everything you want to be included in the if statement:

if(trav->word == word) 
{
    printf("%s found in the dictionary\n", word);
    return true;
}

Otherwise that return true happens every time (and as you saw, without necessarily printing).

Upvotes: 1

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