C：读取多个CSV文件

Question

I need to read a CSV table and use its values for functions, but the scanf() function only reads the first column of the file. I also need the code to be able to read more than one file, not allowing me to specify the name of the file. What would be the correct way of doing so?

Example:

CSV file line: 114 -0.44 -0.15385 -0.76293

Code output: 114 0.00 0.00 0.00

My code:

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

int main(){
    long sec;
    long wait = 0;
    int fall = 0;
    double x;
    double y;
    double z;
    double mag = 0.0;
    long i =0;

    while(1){
        scanf("%ld %lf %lf %lf", &sec, &x, &y, &z);
        mag = sqrt(pow(x,2)+pow(y,2)+pow(z,2));
        break;
    }

    printf("%ld %lf %lf %lf\n", sec, x, y, z);

    output1(wait);
    output2(fall);

    return 0;
}

Answer 1

If you are on Windows OS, you could use dirent.h and create an input directory, where you can store your input files.

Once you have the files you can do a proper handling and start reading lines from it. Since you have a csv file, you can use the strtok to break the line into tokens and then load your variables with them.

Answer 2

The thing stopping you from reading multiple files, is that you're using stdin to read the data rather than opening the files you want? If you're going to be doing the same thing repeatedly but with different input (ie filenames) you should create a function, something along the lines of...

void myfunc(char *filename)
  {
  FILE *thefile;
  double x,y,z;
  long sec;

  thefile=fopen(filename,"r");
  if(thefile)
    {
    if(fscanf(thefile,"%ld %lf %lf %lf", &sec, &x, &y, &z)==4)
      {
      /* do stuff */
      }
    fclose(thefile);
    }
  }

and then in your main you could use the command line arguments to specify the file names like so

int main(int argc,char *argv[])
  {
  int i;
  for(i=1;i<argc;i++)
    {
    myfunc(argv[i]);
    }
  }