asked on

Reading in from a file to a double array

Hi,

I need to be able to read from a file in the format eg.

0
-0.2334
0.48872
0.11330
-0.33340
-0.90202
-0.11133
0.89750
-0.10202
...

And I want it to be stored in a double array. Any ideas how I can do this?

sunnycoder

fscanf () is the shortest and most straight forward way

I, however, would recommend using fgets() to read in data as a string and then use a function like strtod to convert it into double. this provides you more flexibility and reliability. It is easy to perform input data validation using this technique.

sunnycoder

This is the easy way out ..

FILE * fptr;
int i=0;
double arr[100];

fptr = fopen(...);
...
while (fscanf(fptr, "%lf\n", &arr[i]) != EOF )
i++;
...

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brettmjohnson

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smpoojary

#include <stdio.h>
int main()
{
      FILE * fptr;
      int i;
      double arr[100];
      int nTotal;

      if((fptr = fopen("in.txt","r")) == NULL)
      {
            printf("ERROR: Unable to open input file\n");
            return 1;
      }

      i=0;
      while (fscanf(fptr, "%lf\n", &arr[i]) != EOF )
      {
            printf("%lf\n",arr[i]);
            i++;
      }
      nTotal = i;
      printf("Total number of lines = %d",nTotal);
      return 0;
}

furqanchandio

use fscanf to store the number in formatted form