Vfrdtyky

Have to read file.txt with format as mentioned below:
12AA,abc12 n
4CCC,cde15 n

I want to read the file line by line and store comma separated values in separate variables.

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



while(fgets(buffer, 255, (FILE*) fp)) 

{

    fscanf(fp, "%s %s", acc_no, package);

    printf("%sn", acc_no);

    printf("%sn", package);

}



fclose(fp);

I would like not only just read and print the variable but, also, to store them in separate variables. Suggestion on how to do that?

strchr() can help:

while (fgets(str, sizeof str, fp)) {

    char *arr[2], *ptr;



    arr[0] = str;

    if ((ptr = strchr(str, ','))) {

        arr[1] = ptr + 1;

        *ptr = '';

    } else {

        exit(EXIT_FAILURE);

    }

    printf("<%s> <%s>n", arr[0], arr[1]);

}

Notice that you may need to strip the trailing newline lefted by fgets() or ommit the n in printf

If you need to store those strings in fresh memory, then there is a bit more of work, you can realloc() or use a linked list (always prefer linked lists when you don't know the number of lines before-hand):

#include <stdio.h>

#include <stdlib.h>

#include <string.h>



struct node {

    void *data;

    struct node *next;

};



/* Returns a pointer to an allocated string */

extern char *strdup(const char *);



/* Insert a node and returns a pointer to the data */

static void *enqueue(struct node **root, void *data)

{

    struct node *node;



    if (root == NULL) {

        return NULL;

    }

    node = malloc(sizeof *node);

    if (node == NULL) {

        return NULL;

    }

    if (*root == NULL) {

        node->next = node;

    } else {

        node->next = (*root)->next;

        (*root)->next = node;

    }

    node->data = data;

    *root = node;

    return data;

}



/* Delete a node and returns a pointer to the data */

static void *dequeue(struct node **root)

{

    struct node *node;

    void *data = NULL;



    if (root == NULL) {

        return NULL;

    }

    node = *root;

    if (node != NULL) {

        node = node->next;

        data = node->data;

        if (*root == node) {

            *root = NULL;

        } else {

            (*root)->next = node->next;

        }

        free(node);

    }

    return data;

}



int main(void)

{

    struct node *head = NULL;

    char str[256];

    char **arr;

    char *ptr;



    /* While we don't hit EOF */

    while (fgets(str, sizeof str, stdin)) {

        /* Reserve space for 2 pointers */

        arr = malloc(sizeof(*arr) * 2);

        if (arr == NULL) {

            perror("malloc");

            exit(EXIT_FAILURE);

        }

        /* If we find a comma */

        if ((ptr = strchr(str, ','))) {

            /* Store the second string */

            arr[1] = strdup(ptr + 1);

            if (arr[1] == NULL) {

                perror("strdup");

                exit(EXIT_FAILURE);

            }

            /* Strip the string */

            *ptr = '';

        /* If we don't find a comma */

        } else {

            exit(EXIT_FAILURE);

        }

        /* Store the first string */

        arr[0] = strdup(str);

        if (arr[0] == NULL) {

            perror("strdup");

            exit(EXIT_FAILURE);

        }

        /* Add a node to the queue*/

        if (enqueue(&head, arr) == NULL) {

            perror("enqueue");

            exit(EXIT_FAILURE);

        }

    }

    /* While nodes in queue show the data and free */

    while ((arr = dequeue(&head))) {

        printf("%s %s", arr[0], arr[1]);

        free(arr[0]);

        free(arr[1]);

        free(arr);

    }

    return 0;

}

You can use fscanf format strings instead.

fscanf(fp, " %[^,n], %[^n]", values[i][0], values[i][1]);

Like so

#include <stdio.h>



int main() {

    FILE* fp = fopen("file.txt", "r");



    char values[1000][2][100];



    int i = 0;

    while(!feof(fp)) {

      fscanf(fp, " %[^,n], %[^n]", values[i][0], values[i][1]);

      printf("%s %sn", values[i][0], values[i][1]);

    }   



}

The fscanf format string:

• 
  <space> = skip leading whitespaces (like a newline from the line before)


• 
  %[^,n] = read a string until, but not including, "," or "n"


• 
  , = expect a comma and discard it


• 
  %[^n] = read a string until, but not including, "n"

values is a 2D array of strings, with 1000 rows and 2 columns. Each element is a string of maximum length of 100 chars.

Also, if you use %m[^,n] instead, fscanf will allocate the memory for the string read.