Thread: Read file into linked list

hello guys i tried to read file into linked list and then print it
but when i print it the first sentences is deleted .
what am i doing wrong?

Code:

int read_file(char * filename) {	int i = 0;
	int a[20], b[20];
	FILE *fp;
	char line[128];
	LIST *current, *head;
	head = current = NULL;
	fopen_s(&fp, filename, "r");
	if (fp == NULL)
		return 0;
	while (fgets(line, sizeof(line), fp)) {
		LIST *node = malloc(sizeof(LIST));
		node->string = strdup(line);
		node->next = NULL;
		if (head == NULL) {
			current = head = node;
		}
		else {
				current = current->next = node;
				char str[20];
				char* field = strtok(line, ",");
				strcpy(str, field);
				a[i] = (double)atof(str);
				field = strtok(NULL, ",");
				b[i] = (double)atof(field);
				i++;
			}
		}
	fclose(fp);
	printf("Thermic table\nx       y\n======  ======\n");
	for (int k = 0; k < 13; k++)
		printf("%d  %d\n", a[k], b[k]);
	
	printf("\n--------------------------\nLets fly\n--------------------------");
	free_list(head);
	return 1;

my output:15000 8500
1000 10000
19000 20100
35000 40100
23000 30000
25000 42000
300 19000
3000 30000
6000 25000
6000 40000
15000 43000
30000 15555

the real output :
5700,5000
15000,8500
1000,10000
19000,20100
35000,40100
23000,30000
25000,42000
300,19000
3000,30000
6000,25000
6000,40000
15000,43000
30000,15555

Originally Posted by cbeginner12334

hello guys i tried to read file into linked list and then print it
but when i print it the first sentences is deleted .
What am i doing wrong?

Code:

int read_file(char * filename) {    int i = 0;
    int a[20], b[20];
    file *fp;
    char line[128];
    list *current, *head;
    head = current = null;
    fopen_s(&fp, filename, "r");
    if (fp == null)
        return 0;
    while (fgets(line, sizeof(line), fp)) {
        list *node = malloc(sizeof(list));
        node->string = strdup(line);
        node->next = null;
        if (head == null) {
            current = head = node;
        }
        else {
                current = current->next = node;
                char str[20];
                char* field = strtok(line, ",");
                strcpy(str, field);
                a[i] = (double)atof(str);
                field = strtok(null, ",");
                b[i] = (double)atof(field);
                i++;
            }
        }
    fclose(fp);
    printf("thermic table\nx       y\n======  ======\n");
    for (int k = 0; k < 13; k++)
        printf("%d  %d\n", a[k], b[k]);
    
    printf("\n--------------------------\nlets fly\n--------------------------");
    free_list(head);
    return 1;

my output:15000 8500
1000 10000
19000 20100
35000 40100
23000 30000
25000 42000
300 19000
3000 30000
6000 25000
6000 40000
15000 43000
30000 15555

the real output :
5700,5000
15000,8500
1000,10000
19000,20100
35000,40100
23000,30000
25000,42000
300,19000
3000,30000
6000,25000
6000,40000
15000,43000
30000,15555

help.

Originally Posted by Salem

What do likes 19 to 25 have to do with your linked list?

What does the loop at line 30 have to do with your linked list?

> free_list(head);
That's a good idea.

So apply the same idea and make something like

Code:

    while (fgets(line, sizeof(line), fp)) {
        head = add_to_list(head, line);

Your function has a meandering purpose, factor out things which are not specific to the act of reading data from the file.

line 19-25 need to convert for 2 arrays (i dont know how to do it with linked list)
line 30 print the linked list (?)
i did not understand what is the mean of the function add_to_list
can you explain me ?