Thread: reading a file line by line

Cool problem, here's a quick and dirty solution I came up with to see how it might be done

Code:

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

#define DELIM " =;"

enum { NAME_MARKER = '$', STR_MARKER = '\"', DBL_MARKER = '.' };
enum { STRING, DOUBLE, INT };

struct file_fields {
    struct file_fields *next;
    char *name;
    int field;
    union field_value {
        double d;
        char s[BUFSIZ];
        int i;
    } value;
};

void cleanup(struct file_fields *list);

int main(void)
{
    FILE *in;
    char buf[1000];
    struct file_fields *head;
    struct file_fields *it;
    
    in = fopen("input.txt", "r");
    if (in == NULL)
    {
        perror("File couldn't be opened");
        exit(EXIT_FAILURE);
    }
    
    head = malloc(sizeof (*head));
    if (head == NULL)
    {
        fprintf(stderr, "Memory exhausted\n");
        cleanup(head);
    }
    
    it = head;
    
    while (fgets(buf, sizeof (buf), in))
    {
        char *t;
        char *newline;
        
        it->next = malloc(sizeof (*head));
        if (it->next == NULL)
        {
            fprintf(stderr, "Memory exhausted\n");
            cleanup(head);
        }
        
        it = it->next;

        newline = strrchr(buf, '\n');
        if (newline)
            *newline = '\0';
        
        for (t = strtok(buf, DELIM); t; t = strtok(NULL, DELIM))
        {
            if (*t == NAME_MARKER)
            {
                it->name = malloc(strlen(t) + 1);
                if (it->name == NULL)
                {
                    fprintf(stderr, "Memory exhausted\n");
                    cleanup(head);
                }
                
                strcpy(it->name, t);
            }
            else
            {
                /* Not a name, must be a value */
                if (*t == STR_MARKER)
                {
                    it->field = STRING;
                    strncpy(it->value.s, t, BUFSIZ);
                }
                else if (strchr(t, DBL_MARKER))
                {
                    it->field = DOUBLE;
                    it->value.d = strtod(t, NULL);
                }
                else
                {
                    it->field = INT;
                    it->value.i = strtol(t, NULL, 0);
                }
            }
        }
    }
    
    for (it = head->next; it; )
    {
        int i;
        struct file_fields *save;

        save = it;

        for (i = 1; it && i % 6; i++)
        {
            printf("%-15s", it->name);
            fflush(stdout);

            it = it->next;
        }

        printf("\n");

        it = save;

        for (i = 1; it && i % 6; i++)
        {
            switch (it->field)
            {
            case STRING:
                printf("%-15s", it->value.s);
                break;
            case DOUBLE:
                printf("%-15g", it->value.d);
                break;
            case INT:
                printf("%-15d", it->value.i);
                break;
            }

            it = it->next;
        }

        printf("\n\n");
    }

    cleanup(head);

    return 0;
}

void cleanup(struct file_fields *list)
{
    struct file_fields *forward;

    while (list)
    {
        forward = list->next;
        
        free(list->name);
        free(list);
        
        list = forward;
    }

    exit(0);
}

And yes, I know main is way too long.