save a spicific column from a csv file into an array

if i have a file.txt with comma separated value and i need to access the 10th and 15th columns ofthis file and save each one in an array
i tried this code (which was attached in the site) but it didn't work it always print the 3rd column of the file and i still don't know why!!

Code:

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#include <stdio.h>
#include <stdlib.h>

#define FIRST_LINE  0
#define LAST_LINE 10

int main() {

 char buf[512];
  int line_count = 0;
  FILE *file = fopen("min_chest.txt", "r");


  while (fgets(buf, sizeof buf, file) != NULL) {
    double value;

    if (sscanf(buf, "%*lf,%*lf,%lf,*%lf,%lf", &value) != 1) {
      fprintf(stderr, "sscanf failed.\n");
      exit(EXIT_FAILURE);
    }

    printf("%f\n", value);
    if (line_count++ >= 10)
      break;
  }

  fclose(file);


  return 0;
}

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it was refreenced here

https://cboard.cprogramming.com/c-programming/161380-reading-values-csv-file-c-into-array.html

why it always prints the 3rd column ?
and if i need to know the size of the file automatically how to know that ??
any advice of how to get it well ?

Code:

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src/test.cpp:17:53: error: format ‘%lf’ expects a matching ‘double*’ argument [-Werror=format=]
src/test.cpp:17:53: error: format ‘%lf’ expects a matching ‘double*’ argument [-Werror=format=]

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You are trying to read 2 double values of 5, but provide only 1 variable. This is undefined behavior. So your are lucky your program works at all. Fix it before asking why it does something specific.

am sorry i don't understand what u mean ??
"You are trying to read 2 double values of 5, but provide only 1 variable." ??

Code:

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if (sscanf(buf, "%*lf,%*lf,%lf,*%lf,%lf", &value) != 1)

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What is this line supposed to do ?

Quote:

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Originally Posted by OldGuy2

What is this line supposed to do ?

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Quoted from scanf - C++ Reference

Quote:

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An optional starting asterisk indicates that the data is to be read from the stream but ignored (i.e. it is not stored in the location pointed by an argument).

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Looking at the OP's code again though, I think they made a typo there. They meant for all reads except one to have an asterisk.

Quote:

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Originally Posted by Tasneem Gamal

am sorry i don't understand what u mean ??
"You are trying to read 2 double values of 5, but provide only 1 variable." ??

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%*lf will skip the number in the input stream

%lf will read a number into double variable (passed by pointer)

You have 3 %*lf and 2 %lf - it means you expect to have 5 double values and read 2 of them.

To read 2 values you need 2 variables