Thread: Function always returning 0

The statement is:
Write a program that prints all entities of the form &name; (where name is formed of letters) appearing in the input, separated by one space.

Code:

Code:

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#define MAX 100
int checkWord(char word[])
{
    size_t len = strlen(word);
    for(int i = 0; i < strlen(word); i++)
    {
        if(!isalpha(word[i]) || (word[0] != '&') || (word[len-1] != ';'))
        {
            return 0;
        }
    }
    return 1;
}
int main()
{
    char s[MAX];
    while(fgets(s, MAX, stdin))
    {
        char* word = strtok(s, " ");
        while(word != NULL)
        {
           // printf("%s\n", word);
           printf("%d\n", checkWord(word));
            if(checkWord(word) == 1)
            {
                printf("%s ", word);
            }
            word = strtok(NULL, " ");
            //printf("%s", word);
        }
    }
    return 0;
}

The program should work well but checkWord always returns 0 and never actually enters the if block. I don't understand what I'm missing, checkWord checks if the word is formed by letters only, starts with '&' and ends ';' but for the input:
john goes to &school; everyday
Output:
0
0
0
0 // this should be 1 and therefore &school; should be printed
0

What am I doing wrong?

Originally Posted by laserlight

The check for '&' and ';' should be done just once, outside of the loop. You'll just need to adjust the start and end conditions of the loop to avoid checking them in the loop, because that's why your current checkWord returns 0: isalpha(word[0]) would be 0 for a valid input. (Speaking of which, if you should have used len rather than strlen(word) in the loop condition, though now it'll be len-1.)

so my function now looks like this

Code:

int checkWord(char word[])
{
    size_t len = strlen(word);
    if(word[0] != '&' || word[len-1] != ';')
        return 0;
    else
        return 1;
    for(int i = 1; i < len-1; i++)
    {
        if(!isalpha(word[i]))
        {
            return 0;
        }
    }
    return 1;
}

which, is still not working, I've also tried putting the for loop inside the if block but it still returns 0.

Yeah, I added that afterwards because I didn't know what else to try, but it doesn't work without it either.

Code:

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#define MAX 100
int checkWord(char word[])
{
    size_t len = strlen(word);
    if(word[0] != '&' || word[len-1] != ';')
        return 0;
    for(int i = 1; i < len-1; i++)
    {
        if(!isalpha(word[i]))
        {
            return 0;
        }
    }
    return 1;
}
int main()
{
    char s[MAX];
    while(fgets(s, MAX, stdin))
    {
        char* word = strtok(s, " ");
        while(word != NULL)
        {
           // printf("%s\n", word);
           printf("%d\n", checkWord(word));
            if(checkWord(word) == 1)
            {
                printf("%s\n", word);
            }
            word = strtok(NULL, " ");
            //printf("%s", word);
        }
    }
    return 0;
}

Input: &john; goes to &school; everyday by &bus;
Output:
1
&john;
0
0
1
&school;
0
0
0
Expected Output:
1
&john;
0
0
1
&school;
0
1
&bus;




Input: john goes to &school;
Output:
0
0
0
0
Expected Output:
0
0
0
1
&school;

So yes, you're right, it's printing the right output for the input I've put in the example, but it seems that my program doesn't return 1 unless there is another word after &name;. It didn't print any "1" for me because I only tried the second input after modifying the code.

Originally Posted by laserlight

You need to remove the trailing newline character that fgets reads and stores in the string.

It's working now, thank you!