Thread: Reading data from a text file

I've got a text file that has 2 columns and 35 rows of numbers. I am trying to read in the text file and output the 2 columns and 35 rows. With my code I am only getting the last two pieces of data from the file and it's printing the same data 35 times. Any thoughts?

Code:

#include <stdio.h>
int main()
{
int i,j;
float x,y;
FILE *fp;
 fp=fopen("Data.txt", "rb");
for(j=0; j<35; j++)
 for(i=0; i<2; i++)
 fscanf(fp,"%f, %f", &x, &y);
for(j=0; j<35; j++)
 for(i=0; i<2; i++)
  
  printf("%f  %f\n", x, y);
fclose(fp);
return 0;
}

I had this earlier, but it wasn't working either. Is it any closer? I appreciate your help. I'm still learning.

Code:

#include <stdio.h>
int main()
{
int i,j;
double data[2][35];
FILE *fp;
 fp=fopen("Data.txt", "r");
for(j=0; j<35; j++)
 for(i=0; i<2; i++)
 fscanf(fp,"%lf, %lf", &data[i][j]);
for(j=0; j<35; j++)
 for(i=0; i<2; i++)
  
  printf("%f  %f\n",data[i][j]);
fclose(fp);
return 0;
}

Does it give you the output you expect? Why are you using %lf for input but %f for output?

It looks like the output is correct for the first column, but the second column is a REALY long number and it just repeats itself on each row. I changed the output to %lf and it still gives me the wrong answer for the second row.

It just doesn't seem to be reading the numbers in the second column properly. I've tried editing the text file with a space between the numbers on each row and with a comma in between. It seems to like have a comma better.

It should just be two columns. I'm reading two numbers at a time becuase that's what I thought I needed to get each column. Here's a sample of what the text file looks like.

2.05,293.21
1.60,299.16
1.37,182.14
0.76,163.41
0.99,200.43
0.53,86.39
1.14,225.11

Ok, I think I've almost got it. The only problem is that it is outputting the last row of numbers from the text file twice. Here's my revised code.

Code:

#include <stdio.h>
int main()
{
int i, n, gotnum;
FILE *fp;
float col1[35];
float col2[35];
fp=fopen("Data.txt", "r");
 i=0;
 do
 {
  gotnum=0;
  gotnum=fscanf(fp,"%f %f", &col1[i], &col2[i]);
  if(gotnum>1);
  printf("%10.2f  %10.2f\n", col1[i], col2[i]);
 
 }
 while(gotnum>1);
  
fclose(fp);
return 0;
 }

Here's what the last part of the output is doing:

2.51 367.25
2.13 345.55
1.90 268.52
2.36 422.57
2.36 422.57

Actually got it! Here's what I ended up with.

Code:

#include <stdio.h>
int main()
{
int i;
FILE *fp;
float col1[35];
float col2[35];
fp=fopen("Data.txt", "r");
 for(i=0; i<35; i++)
  fscanf(fp,"%f %f", &col1[i], &col2[i]);
 for(i=0; i<35; i++)
  printf("%10.2f  %10.2f\n", col1[i], col2[i]);
  
fclose(fp);
return 0;
}

Thanks for the pointers!