Hi. I'm having problems about my program. My program is something like a directory. It takes in values for different fields and stores it in a linked list in a sorted manner. It also allows the user to save the linked list contents to a text file. Everything runs okay except for the function that checks the file existence and if it exists, it reads the file and stores its contents to a linked list before inserting the new node which contains the recent user-input.

Here is my copyFiletoList and insert function:

void copyFiletoList(nodePtr *start){

    nodePtr newPtr, prevPtr, curPtr;
    RecordNode temp;
    nodePtr fPtr;
    char lN[30]="\0";
    char fN[30]="\0";
    char mN[30]="\0";
    char cE[30]="\0";
    char sN[30]="\0";
    char cN[30]="\0";

    fp = fopen("directory.txt", "r");

    fPtr = *start;


        fread(&temp, (sizeof(struct recordNode)-1), 1, fp);
            fscanf(fp," %[^\n] %[^\n] %[^\n] %[^\n] %[^\n] %[^\n]", temp.Name, temp.fName, temp.mName, temp.course, temp.sNum, temp.cNum);
        insert(&fpTr, temp.Name, temp.fName, temp.mName, temp.course, temp.sNum, temp.cNum);



void insert(nodePtr *start, char lName[30], char f[30], char m[30], char c[30], char s[10], char cN[10]){

    nodePtr newPtr, prevPtr, curPtr;

    newPtr = malloc(sizeof(struct recordNode));

    if(newPtr != NULL){

        strcpy(newPtr->Name, lName);
        strcpy(newPtr->fName, f);
        strcpy(newPtr->mName, m);
        strcpy(newPtr->course, c);
        strcpy(newPtr->sNum, s);
        strcpy(newPtr->cNum, cN);
        newPtr->nextPtr = NULL;

        prevPtr = NULL;
        curPtr = *start;

        while(curPtr!=NULL && strcmp(lName,curPtr->Name)==1){
            prevPtr = curPtr;
            curPtr = curPtr->nextPtr;

        if(prevPtr == NULL){
            /*Insert at the beginning*/
            newPtr->nextPtr = *start;
            *start = newPtr;
            /*Insert at the middle*/
            prevPtr->nextPtr = newPtr;
            newPtr->nextPtr = curPtr;
        printf("Memory insufficient. Cannot insert.\n");

The whole program compiles and runs fine without any error, but when I try to display the whole linked list, it only displays the recent data from input even though the file already has contents prior to the run. Please help me. Thank you.

4 Years
Discussion Span
Last Post by songseungun

Your program is not checking for the existance if the file, it just assumes the file always exists. You need to check for NULL return from fopen() and do nothing if NULL was returned.

BTW: Don't call rewind() after fopen() because its a waste of effort, the file pointer is already at the beginning of the file.


I call the function after checking for the file existence. So it only does it to copy the contents. What I am after is why does this function does not seem to copy anything at all hence only the recent user input is the content of the linked list.


Finally got to solve my problem. I used fscanf instead. Thanks for the help.

 if((fp = fopen("directory.txt", "r"))!=NULL){
            printf("-------------------------\n::FILE EXISTENCE CHECK::\n-------------------------\n");
            printf("File: directory.txt exists. Copying file contents...\n");

                    if(fscanf (fp, " %[^\n] %[^\n] %[^\n] %[^\n] %[^\n] %[^\n]", lastName, firstName, midName, course, studNum, contactNum) != EOF){
                        insert(&sPtr, lastName, firstName, midName, course, studNum, contactNum);

            printf("File contents copied. \n\n");

            printf("--------------------------\n ::FILE EXISTENCE CHECK::\n--------------------------\n");
            printf("File: directory.txt does not exist.\n\n");
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