Issue with fscanf reading input file

0
votes

I am trying to convert an input file from .txt to .csv. I've performed multiple tests using gdb and switched my code around. The code looks like it should work but for some reason it doesn't. I've tried using "while (fscanf(…arguments…) != EOF)" but I always end up in a never-ending loop when I know that the input file does end. Is it the way I'm trying to read the file that's the problem or something else? I'd greatly appreciate any advice.

A sample of the input file (it's way too big. Also the potentiometer value is the only value that is consistently zero. All other values are greater than zero)

time:  40 ms
switch0: 1
switch1: 1
switch2: 1
switch3: 1
potentiometer: 0.00
temperature: 0.66
light: 0.23

---------------------------

time:  80 ms
switch0: 1
switch1: 1
switch2: 1
switch3: 1
potentiometer: 0.00
temperature: 0.66
light: 0.23

---------------------------

time:  120 ms
switch0: 1
switch1: 1
switch2: 1
switch3: 1
potentiometer: 0.00
temperature: 0.66
light: 0.23

---------------------------

The file that convert from txt to csv

1 #include <stdio.h>
2 #include <stdlib.h>
3
4 int main()
5 {
6         FILE *data = fopen("data.csv","w");
7         FILE *arduino = fopen("arduino.txt","r");
8
9         if(arduino == NULL)
10         {
11             printf("error reading file\n");
12             return 1;
13         }
14         if(data == NULL)
15         {
16             printf("error writing file\n");
17             return 2;
18         }
19
20         fprintf(data,"Time,Switch0,Switch1,Switch2,Switch3,Potentiometer,Temperature,Light\n");
21
22         int num1,num2,num3,num4,num5;
23         double num6,num7,num8;
24
25         double temp1[800];
26
27         int count1 = 0;
28
29         while(count1<800)
30         {
31             fscanf(arduino,"%lf",&temp1[count1]);
32             count1++;
33         }
34
35         for(count1 = 0; count1 < 800; count1++)
36         {
37             printf("%lf",temp1[count1]);
38         }
39
40
41         int count2 = 0;
42         int i = 0;
43
44         while(count2 != 800)
45         {
46                 for(i=0 ; i <8;i++)
47                 {
48                         if(i==7)
49                         {
50                                 fprintf(data,"%lf\n",temp1[count2]);
51                         }
52
53                         else
54                         {
55                                 fprintf(data, "%lf,", temp1[count2]);
56                         }
57                         count2++;
58                 }
59         }
60
61
62         if (fclose(arduino)==EOF)
63         {
64                 printf("error closing input file\n");
65         }
66         if(fclose(data)==EOF)
67         {
68                 printf("error closing output file\n");
69         }
70 }

and here's the output

Time,Switch0,Switch1,Switch2,Switch3,Potentiometer,Temperature,Light
  2 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
  3 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
  4 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
  5 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
  6 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
  7 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
  8 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
  9 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 (still zeros across the board)
 61 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 62 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 63 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 64 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 65 0.000000,0.000000,0.000000,0.000000,-nan,0.000000,0.000000,0.000000
 66 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 67 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 68 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 69 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 70 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 71 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 72 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 73 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 74 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 75 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 76 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 77 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 78 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 79 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 80 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 81 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 82 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 83 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 84 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 85 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 86 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 87 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 88 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 89 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 90 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 91 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 92 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 93 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 94 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 95 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 96 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 97 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 98 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 99 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
 100 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,253700437344304240814662650531587413567701629019053044079803999006261210888228446189339915094527360    92923426425002851172634311446770729875573243622981632.000000,49038509684686202755808411764574575003743211375155249005916427827780247417991687082747214451    073341675744581253991867335918252416362555908299070786942125737694751726823604090062182039519355613866611467434357822207669472484839486934106348907556279    40839424.000000
101 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
1
cscanf
check return value of fscanf. Reading numerical values will fail if there is a character string. - BLUEPIXY
In future, please don't put line numbers on the code; it makes it hard to make a copy and test. Please review the layout of the data; are there blank lines either side of the dashed line? Is there really a dashed line in the data? It is worth using more spaces in your code, after commas in particular. - Jonathan Leffler
The first line contains a string (time:), a number (40), and another string (ms). So the first fscanf needs to use a format string like "%*s%lf%*s". Note that fscanf isn't going to skip the strings, unless you tell it to. - user3386109
Note that fscanf() returns 0 when it can't match anything — it only returns EOF when there is no data left. It does not discard unrecognizable data. - Jonathan Leffler
If it doesn't return EOF, fscanf()returns the number of values it has successfully read. That number can be less than the number specified in the format string if an error occurs. Depending on what error has occurred (e.g. encountering a character like 'Q' when the format string specifies a float) looping on fscanf != EOF can yield an infinite loop, unless other checks are done. - Peter

1 Answers

2
votes

Checking the return value from fscanf() against the expected value, not against EOF is a good idea. @BLUEPIXY @Peter. This will identify/solve most of OP's problems.

The data file has keywords in it, they needed to be scanned too. @user3386109

Suggest direct code to read the entire record with one fscanf().

struct kk {
  int time;
  int switchn[4];
  double potentiometer, temperature, light;
};

int data_kk_read(FILE *inf, struct kk *data) {
  int cnt = fscanf(inf,
      " time: %d ms switch0: %d switch1: %d switch2: %d"
      " switch3: %d potentiometer: %lf temperature: %lf light: %lf"
      " --------------------------- ",
      &data->time,&data->switchn[0],&data->switchn[1], &data->switchn[2],
      &data->switchn[3], &data->potentiometer, &data->temperature, &data->light);
  return cnt;
}

int data_kk_write(FILE *outf, unsigned n, const struct kk *data) {
  int cnt = fprintf(outf,
      "%3u %d, %d, %d, %d, %d, %.2lf, %.2lf, %.2lf\n", n,
      data->time, data->switchn[0], data->switchn[1], data->switchn[2],
      data->switchn[3], data->potentiometer, data->temperature, data->light);
  return cnt;
}

int main(void) {
  FILE *inf = fopen("data.txt", "r");
  assert(inf);
  unsigned line = 0;
  struct kk data;
  int cnt;
  while ((cnt = data_kk_read(inf, &data)) == 8) {
    data_kk_write(stdout, ++line, &data);
  }
  fclose(inf);
  if (cnt != EOF) puts("Unexpected scanning problem");
  return 0;
}

Output

  1 40, 1, 1, 1, 1, 0.00, 0.66, 0.23
  2 80, 1, 1, 1, 1, 0.00, 0.66, 0.23
  3 120, 1, 1, 1, 1, 0.00, 0.66, 0.23