Thread: Printing word from a txt file (platform: UNIX)

Hi
The following code is supposed to print the words(txt) from a file to stdout. I am using Double Linked list cause I am asked to do so. But the problem is... (marked by ERROR in the code listing), when I run it it gives me a seg fault. instead of using %s if I use %c as mentioned inside, I can only print the 1st char of the words. How can I fix it.. please please

****************************

Code:

#include <stdio.h>
#define  NullChar    '\0'
#define  NewLine     '\n'

struct NODE
{
   struct NODE *pNext;
   struct NODE *pPrev;
   char* nData;
}*pHead, *pTail;

void AppendNode(struct NODE *pNode);
void InsertNode(struct NODE *pNode, struct NODE *pAfter);

void AppendNode(struct NODE *pNode)
{
    if (pHead == NULL) {
        pHead = pNode;
        pNode->pPrev = NULL;
    }
    else {
        pTail->pNext = pNode;
        pNode->pPrev = pTail;
    }
    pTail = pNode;
    pNode->pNext = NULL;
}


void InsertNode(struct NODE *pNode, struct NODE *pAfter)
{
    pNode->pNext = pAfter->pNext;
    pNode->pPrev = pAfter;

    if (pAfter->pNext != NULL)
        pAfter->pNext->pPrev = pNode;
    else
        pTail = pNode;
    pAfter->pNext = pNode;
}



void main()
{
    struct  NODE *pNode;
    int i;

    FILE *instream=fopen("words.csv","r");

    char *word[100];
    int k=0;

    while(k != -1)
        {
            pNode = malloc (sizeof (struct NODE));
            k= pNode->nData = getword(word,100,instream);;
            AppendNode(pNode);
        }
/*ERROR HERE ::STARTS (only prints one char if used %c else give seg error if used %s*/
 for( pNode=pHead;pNode !=Null; pNode=pNode->nNext)
 {
   printf("%s",pNode->nData);
 }
/*ERROR HERE::ENDS*/

}


/* getword:  get next word or character from input */
int getword(char *word, int lim, FILE * instream)
{
    int c;
    char *w = word;
    while ((isspace(c = fgetc(instream))) && (c !='\n'))
        ;


    if (c != EOF)
        *w++ = c;

    if (!isalpha(c) ) {
        *w = NullChar;
        return c;
    }

    for ( ; --lim > 0; w++)
        if (!isalnum(*w = fgetc(instream))) {
            ungetc(*w,instream);
            break;
        }
    *w = NullChar;
    if (c == EOF)
        return EOF;
    return word[0];
}

<< !! Posting Code? Read this First !! >>

Originally Posted by bithub

Code:

char *word;
    int k=0;

    while(k != -1)
        {
            word = malloc(100 * sizeof(char));
            pNode = malloc (sizeof (struct NODE));
            k= pNode->nData = getword(word,100,instream);;
            AppendNode(pNode);
        }

sizeof(char) is guaranteed to be 1. It might be appropriate to do something like this:

Code:

word = malloc(100 * sizeof(*word));

~/

> k= pNode->nData = getword(word,100,instream);
Do you even get any warnings from this?

It would be better for getword to return a char* (and hence return NULL at the end of input) than what you are doing at the moment.

Code:

#include <stdio.h>
#include <stdlib.h>             /* for malloc */
#include <ctype.h>

#define  NullChar    '\0'
#define  NewLine     '\n'

struct NODE {
    struct NODE *pNext;
    struct NODE *pPrev;
    char *nData;
} *pHead, *pTail;

void AppendNode(struct NODE *pNode);
void InsertNode(struct NODE *pNode, struct NODE *pAfter);
char *getword(char *word, int lim, FILE * instream);

void AppendNode(struct NODE *pNode)
{
    if (pHead == NULL) {
        pHead = pNode;
        pNode->pPrev = NULL;
    } else {
        pTail->pNext = pNode;
        pNode->pPrev = pTail;
    }
    pTail = pNode;
    pNode->pNext = NULL;
}


void InsertNode(struct NODE *pNode, struct NODE *pAfter)
{
    pNode->pNext = pAfter->pNext;
    pNode->pPrev = pAfter;

    if (pAfter->pNext != NULL)
        pAfter->pNext->pPrev = pNode;
    else
        pTail = pNode;
    pAfter->pNext = pNode;
}



int main()
{                               /* main returns int - AWLAYS! */
    struct NODE *pNode;
    FILE *instream = stdin /*fopen("words.csv","r") */ ;
    char *word;
    char *k = 0;

    do {
        word = malloc(100 * sizeof *word);
        pNode = malloc(sizeof *pNode);
        k = pNode->nData = getword(word, 100, instream);
        AppendNode(pNode);
    } while ( k != NULL );
/*ERROR HERE ::STARTS (only prints one char if used %c else give seg error if used %s*/
    for (pNode = pHead; pNode != NULL; pNode = pNode->pNext) {
        printf("%s\n", pNode->nData);
    }
/*ERROR HERE::ENDS*/
    return 0;
}


/* getword:  get next word or character from input */
char *getword(char *word, int lim, FILE * instream)
{
    int foundword = 0;
    char *w = word;
    while ( lim > 0 ) {
        int c = fgetc(instream);
        if ( c == EOF ) { word = NULL; break; }
        if ( !foundword && isspace(c) ) continue;
        foundword = 1;
        if ( isalnum(c) ) {
            *w++ = c;
            *w = NullChar;
            lim--;
        } else {
            ungetc(c, instream);
            break;
        }
    }
    return word;
}

Sort of works, there are a couple of things to fix.