Thread: Yet more Pointers and Linked List Questions

Hello All

I have written tis program to read the words from a text file and simply count the number of occurrences each word has. I'm still trying to get to grips with the whole pointer and freeing up the memory afterwards principle.

Could you please check out my listing a let me know if I have sucessfuly freed up all the malloc'd memory.

Many thanks

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define NOTFOUND 0
#define FOUND 1

struct TheWord *AddNodeToList(char *);
void showAllNode(struct TheWord *);
struct TheWord *FindAWord(struct TheWord *, char *);
void freeAllNode(struct TheWord *);

struct TheWord
{
    struct  TheWord *nextWord;
    char    theWord[100];
    int     theWordCounter;
};

int main(int args, char *argv[])
{
    int readChar = 0;
    char thisWordBuffer[100]={'\0'};
    int thisWordCounter = 0;
    struct  TheWord *root = malloc(sizeof(*root));
    struct  TheWord *tail;
    struct  TheWord *incrementTheWord;
    /*SETUP AND OPEN THE FILE*/
    FILE *fp;
    /*THE FILE CAN BE ANY TEXT FILE FOR WHICH YOU WANT TO COUNT THE NUMBER OF OCCURANCES OF WORDS*/
    if((fp = fopen("I:\\C\\text.txt","r"))==NULL) {
        printf("Error:Can't open file");
        exit(-1);
    }
    /*CREATE THE ROOT NODE*/
    root->nextWord = NULL;
    strcpy(root->theWord,"root");
    root->theWordCounter = 0;
    tail = root;
    /*READ THE FILE UNTI EOF*/
    while((readChar = fgetc(fp))!=EOF) {
        /*IF THE CHAR READ IS NOT A PART OF A WORD I.E. A-Z*/
        if(readChar!=' ' && readChar!='\n' && readChar!='.' && readChar!=',') {
            thisWordBuffer[thisWordCounter] = readChar;
            thisWordCounter++;
        }
        else {
            /*ADD THE TERMINATOR*/
            thisWordBuffer[thisWordCounter]='\0';
            /*REINITIALISE THE COUNTER*/
            thisWordCounter = 0;
            /*IF THE WORD IS ALREADY IN THE LIST*/
            if((incrementTheWord = FindAWord(root,thisWordBuffer))!=NULL) {
                /*INCREMENT THE COUNTER RATHER THAN ADD THE WORD AGAIN*/
                incrementTheWord->theWordCounter++;
            }
            else {
                /*IF THE WORD IS NOT IN LIST, ADD IT*/
                tail->nextWord = AddNodeToList(thisWordBuffer);
                /*KEEP THE TAIL MARKER UPTODATE*/
                tail = tail->nextWord;
            }
        }
    }
    showAllNode(root);
    freeAllNode(root);
    free(root);
    return 0;
}

struct TheWord *AddNodeToList(char *wordToAdd)
{
    /*CREATE A NEW STRUCURE AND GIVE IT SOME MEM*/
    struct TheWord *newNode = malloc(sizeof(*newNode));
    int x = 0;
    /*INITIALISE TO NULL AS THIS IS END NODE*/
    newNode->nextWord = NULL;
    /*ITERATE THROUGH THE WORD UNTIL '\0'*/
    while(*wordToAdd) {
        newNode->theWord[x] = *wordToAdd;
        x++;
        wordToAdd++;
    }
    /*ADD THE TERMINATOR - I'LL BE BACK!*/
    newNode->theWord[x]='\0';
    /*SET THE COUNTER TO ONE AS THIS SHOULD BE FIRST ADDITION TO THE LIST*/
    newNode->theWordCounter = 1;
    /*RETURN THE NODE*/
    return newNode;
}

void showAllNode(struct TheWord *rootNode)
{
    /*ITERATE THROUGH ALL THE NODES FROM THE GIVEN ROOT*/
    while(rootNode = rootNode->nextWord) {
        printf("The Word [%20s] LISTED \t\t[%d] TIME(S)\n",rootNode->theWord, rootNode->theWordCounter);
    }
}

void freeAllNode(struct TheWord *rootNode)
{
    struct TheWord *temp;
    temp = rootNode->nextWord;
    while(rootNode) {
        temp = rootNode->nextWord;
        free(rootNode);
        rootNode = NULL;
        rootNode = temp;
    }
}

struct TheWord *FindAWord(struct TheWord *rootNode, char *findWord)
{
    int foundStatus = NOTFOUND;
    while((rootNode = rootNode->nextWord) && foundStatus == NOTFOUND) {
        if(strcmp(rootNode->theWord,findWord)==0)
        {
            foundStatus = FOUND;
        }
    }
    return rootNode;
}

Thank you. I'm going to have a look at the Valgrind. Do you have any suggestions regarding its use? Is there a tutorial site you can recommend for it? Can I only run it on my Ubuntu machine or is there a windows version hidden away somewhere?

Cheers