How read a variable number of int from a string - c

Question

I have the following text file
0 0 0 debut
1 120 0 permis exploitation
2 180 1 1 piste 6km
3 3 1 2 installation sondeuses
4 30 1 2 batiments provisoires
5 60 1 2 groudronnage piste
6 90 1 4 adduction eau
7 240 2 3 4 campagne sondage
8 180 3 5 6 7 forage 3 puits
9 240 3 5 6 7 construction bureaux logements
10 30 2 8 9 transport installation matériel
11 360 2 8 9 traçage du fond
12 240 2 8 9 construction laverie
13 0 3 10 11 12 fin des travaux
Each line is the representation of a task and is described as followed: the first number is and ID, the second is the duration, the third is the number of previous tasks that are required, and all the numbers afterward are the IDs of the required tasks. Finaly the string in the end is the title of the string.
I'm trying to fill an array of those struct by reading this file. Here is the struct:
typedef struct{
int id;
int duration;
int nbPrev; /* number of required previous tasks */
int prev[NMAXPREV]; /*array of required previous tasks*/
char title[LGMAX];
}Task ;
Here is my code to read the file
int readTasksFile(char* file_name, Task t[])
{
FILE* f;
char line[256] = {'\0'};
int i = 0;
char c[1] = {0};
if((f = fopen(file_name, "r")) == NULL)
{
perror("The file couldn't be opened");
exit(EXIT_FAILURE);
}
while (fgets(line, 256, f) != EOF)
{
sscanf_s(line, "&d &d &d", &(t[i].id), &(t[i].duration), &(t[i].nbPrev));
i++;
}
fclose(f);
return 0;
}
How can I read all the previous tasks number in a line considering it is variable and still be able to read the title afterward ?

Answer 1

How can I read all the previous tasks number in a line considering it is variable and still be able to read the title afterward ?
The 3rd int should be the number of following ints.
Use "%n" to record scan offset.
After reading the .prev[], copy the rest of the line to .title.
Add error checking. This is very important, especially for complex input.
// Untested code to get OP started
// while (fgets(line, 256, f) != EOF) Comparing against EOF is incorrect
while (fgets(line, sizeof line, f)) {
int offset = 0;
// Use %d, not &d
if (sscanf(line, "%d %d %d %n",
&t[i].id, &t[i].duration, &t[i].nbPrev, &offset) != 3) {
// Handle bad input, for now, exit loop
break;
}
if (t[i].nbPrev < 0 || t[i].nbPrev > NMAXPREV) {
// Handle bad input, for now, exit loop
break;
}
char *p = line + offset;
int prev;
// Populate t[i].prev[]
for (prev = 0; prev < t[i].nbPrev; prev++) {
if (sscanf(p, "%d %n", &t[i].prev[prev], &offset) != 1) {
break;
}
p += offset;
}
if (prev != t[i].nbPrev) {
// Handle bad input, for now, exit loop
break;
}
// remaining text
int len = strlen(p);
if (len > 0 && p[len-1] == '\n') p[--len] = '\0'; // consume potential trailing \n
if (len >= LGMAX) {
// Handle bad input, for now, exit loop
break;
}
strcpy(t[i].title, p);
i++;
}
return i; // Let caller know of successful lines parsed.
Advanced: robust code would use strtol() instead of "%d" and sscanf().
readTasksFile() should also pass in the max number of Task t[] that can be read.

Answer 2

You could also scan by line and assign the two first numbers to id and duration, then do an int analysis and add the rest of the elements to nbPrev until you encounter a letter.
I don't know if this would be the best way to do it, but it's how I would do it.
Why don't you create also a list each time you register in struct nbPrev?
Like, instead of nbPrev being of type int, make it of type list?