如何读取文本文件并将其存储在 C 编程中的数组中（以逗号分隔的值）？

Question

I need help with getting datapoints, x and y values from a txt file into two arrays.

Currently, the text file consists of 5 lines like:

0.116

0.118

0.12

0.122

0.124

This is my code:

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

main(void) 
{
   FILE *inp;         /* pointer to input file */

   double item;
  int cnt=0,y,d,i;
   double array[300],swap;  

   /* Prepare files for input */
   inp = fopen("testdoc.txt", "r");


   /* Read each item */
   while ( (fscanf(inp, "%lf", &item) == 1) && (!feof(inp)) ) {
     array[cnt] = item;
     cnt++; 
   }


   for (int i = 0; i < cnt; i++)
   {
      printf("%lf\n",array[i]);

   }
   printf("The total number of inputs is %d",cnt);


  fclose(inp); /* Close the files */

  return (0);
}

This only reads the first half of the file, which are the x values. Of which output is

0.116000

0.118000

0.120000

0.122000

The total number of inputs is 4

However, I want to read a text file and store the values in two different arrays for x and y values.

The new text file will look like this

0.116,-0.84009

0.118,4.862

0.12,-1.0977

0.122,0.22946

0.124,3.3173

How do i go changing my code above to recognize the Y values after "," sign? And to add both into two arrays at once?

Answer 1

I tried compiling your code posted on pastebin and received an error because of a missing bracket in your while statement. That's an easy fix. The larger issue is in the condition of the while loop.

fscanf returns the number of input items converted and assigned on each call.

When you modified your code to return two values, the condition in the while loop fscanf(inp, "%lf,%lf", &v1,&v2) == 1 would fail and the loop will not be entered.

Please modify the while statement to ( have included the missing "(" too )..

while ( (fscanf(inp, "%lf, %lf", &v1, &v2) == 2) && (!feof(inp)) ) and you should be good to go!!!

In addition it would be a good practice to include the return type of int for the main function.