getting error file format incorrect, reading file in c

Question

if i run 1 data, program execution is success. but in 2 data format file incorrect. where did i go wrong?

File .txt

1,Nanggroe Aceh Darussalam,Rumah Sakit,RSU Cut Nyak Dhien,Jl. Tm Bahrum No. 1 Langsa
2,Jawa Barat,Klinik Utama,dr. Sunarhadi,Raya Cikaret No. 12

Read code

do{
    read = fscanf(file,
                    "%d,%100[^,],%100[^,],%100[^,],%100[^,]\n",          
                    &students[records].no, 
                    students[records].prov, 
                    students[records].tipe, 
                    students[records].nama,
                    students[records].alamat); 

    if (read == 5) records++;
    
    if (read != 5 && !feof(file)){
      printf("File format incorrect.\n");
      return 1;
    }
    
    if (ferror(file)){
      printf("Error reading file.\n");
      return 1;
    }

  } while (!feof(file));

Output says

File format incorrect.

How can i output like

No      : 1
Prov    : Nanggroe Aceh Darussalam
Tipe    : Rumah Sakit
Nama    : RSU Cut Nyak Dhien
Alamat  : Jl. Tm Bahrum No. 1 Langsa

No      : 2
Prov    : Jawa Barat
Tipe    : Klinik Utama
Nama    : dr. Sunarhadi
Alamat  : Raya Cikaret No. 12

Parsing lines with `scanf`-like functions is a recipe for disaster. Use `fgets` to get a line, then use whatever to parse that line, you could use `sscanf` if you like. — Cheatah, Dec 13 '22 at 19:45
xNapzm , please post the definition of `students` and its `struct`. — chux - Reinstate Monica, Dec 13 '22 at 20:07
@DevSolar, the use of `feof()` is not the problem here, and in fact is correct in an obscure fashion. Problem is in `"...%100[^,]\n"`. — chux - Reinstate Monica, Dec 13 '22 at 20:22
@chux-ReinstateMonica Sometimes I push my trigger too fast. Didn't see the `feof()` in the middle of the loop. Thanks for reopening. — DevSolar, Dec 13 '22 at 23:30
Note that error messages should be written to `stderr` and not `stdout`. — Jonathan Leffler, Dec 14 '22 at 05:50

Craig Estey · Answer 1 · 2022-12-13T20:06:46.987

3

The format is incorrect. It expects a trailing comma on the lines.

Change:

"%d,%100[^,],%100[^,],%100[^,],%100[^,]\n"

Into:

"%d,%100[^,],%100[^,],%100[^,],%100[^\n]\n"

Notes:

Never use feof. Just check the return value of fscanf and ensure it's equal to 5. See: Why is “while( !feof(file) )” always wrong?
You check ferror but never show what errno is in your printf

edited Dec 13 '22 at 20:06

answered Dec 13 '22 at 20:01

Craig Estey

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And be wary of [trailing white space in `scanf()` format strings](https://stackoverflow.com/q/19499060/15168). Here, where the data comes from a file, it is probably not a problem unless someone is careless enough to provide `/dev/tty` as the file name instead of `file.txt`, but in general, it is a bad idea. – Jonathan Leffler Dec 13 '22 at 21:25

getting error file format incorrect, reading file in c

1 Answers1