Thread: Read lines from a file and save them in a struct, help!

Hello!

I need to read text from a file that is formatted like this:

artist;album;release type;rating

and then save it to a struct that looks like this:

Code:

typedef struct {
        char artist[41];
        char album[41];
        char type[3];
        char rating[5];
} record;

The problem is that I don't really now if I want to use fscanf or fgets and how to put the info in the struct. I also want to put the struct to a list but that's easier I think.

Anyway here is my code:

Code:

#include <stdio.h>
#include <stdlib.h>
#include "dlist.h"
#define BUFSIZE 90


typedef struct {
        char artist[41];
        char album[41];
        char type[3];
        char rating[5];
} record;


void readFile(FILE *infilep, dlist *list);


int main(int argc, char *argv[]) {


        
        FILE * infilep;
        infilep = fopen(argv[1],"r");


        if (infilep == NULL) {
                fprintf(stderr, "Couldn't open input file.");
                exit(1);
        }


        if(argc < 1) {
                fprintf(stderr, "Usage: %s <musik.txt>\n", argv[0]);
                exit(1);
        }




        
        dlist *list=dlist_empty();
        dlist_setMemHandler(list, free);


        
        readFile(infilep, list);


        return 0;
}

void readFile(FILE *infilep, dlist *list) {


        char line[BUFSIZE];
        dlist_position pos;
        pos = dlist_first(list);


   
        while (fgets(line, BUFSIZE, infilep) =! NULL) {
                record *info=malloc(sizeof(record));
                fgets(infilep, "%41[^;]%41[^;]%3[^;]%5[^;]",
                       &info->artist, &info->album,
                       &info->type, &info->rating);
                dlist_insert(list, pos, record);
                dlist_next(list, pos);
        }
}

Help appreciated!

Thanks

Instead of that second fgets() call, I think you meant this, which I think should work:

Code:

    if (info == NULL)
        { /* error! */ }
    memset(record, 0, sizeof(record)); /* In case of missing fields */
    sscanf(line, "%41[^;]%41[^;]%3[^;]%5[^;]",
           &info->artist, &info->album, &info->type, &info->rating);

Also, in main(), you should check "(argc < 1)" before trying to open the file. Otherwise you could be passing a NULL pointer to fopen(), which might crash.

Originally Posted by KenJackson

Instead of that second fgets() call, I think you meant this, which I think should work:

Code:

    if (info == NULL)
        { /* error! */ }
    memset(record, 0, sizeof(record)); /* In case of missing fields */
    sscanf(line, "%41[^;]%41[^;]%3[^;]%5[^;]",
           &info->artist, &info->album, &info->type, &info->rating);

Also, in main(), you should check "(argc < 1)" before trying to open the file. Otherwise you could be passing a NULL pointer to fopen(), which might crash.

Thanks alot guys. I kind of understand how fgets and sscanf works now. But when I try to compile gcc says

"audiofil.c: In function `readFile':audiofil.c:72: error: invalid lvalue in assignment
audiofil.c:76: warning: char format, different type arg (arg 3)
audiofil.c:76: warning: char format, different type arg (arg 4)
audiofil.c:76: warning: char format, different type arg (arg 5)
audiofil.c:76: warning: char format, different type arg (arg 6)
audiofil.c:77: error: syntax error before "record""

What does that mean?

readFile looks like this now (I'll add memset and stuff later):

Code:

void readFile(FILE *infilep, dlist *list) {


        char line[BUFSIZE];
        dlist_position pos;
        pos=dlist_first(list);

        while (fgets(line, BUFSIZE, infilep) =! NULL) {
                record *info=malloc(sizeof(record));
                sscanf(line, "%41[^;]%41[^;]%3[^;]%5[^;]",
                       &info->artist, &info->album,
                       &info->type, &info->rating);
                dlist_insert(list,pos,record);
                dlist_next(list,pos);
        }
}