I am writing a command-line C program to perform cubic-pline interpolation on large data files.  Each line of the ASCII files will have: x-value,y-value.  The values will be converted to long doubles via _atold and then put into separate x-arrays and y-arrays.

I can probably eventually write code to properly input the data, but I am hoping someone already has a solid routine for doing it.

Thanks in advance for your help.

rvw

rvw wrote:
> I am writing a command-line C program to perform cubic-pline interpolation on
> large data files.  Each line of the ASCII files will have: x-value,y-value.  The
> values will be converted to long doubles via _atold and then put into separate
> x-arrays and y-arrays.
> 
> I can probably eventually write code to properly input the data, but I am hoping
> someone already has a solid routine for doing it.
> 
> Thanks in advance for your help.
> 
> rvw
> 
> 
fscanf?


-- 
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Jan Knepper

But as for me and my household, we shall use Mozilla...
www.mozilla.org

rvw wrote:
> I am writing a command-line C program to perform cubic-pline interpolation on
> large data files.  Each line of the ASCII files will have: x-value,y-value.  The
> values will be converted to long doubles via _atold and then put into separate
> x-arrays and y-arrays.
> 
> I can probably eventually write code to properly input the data, but I am hoping
> someone already has a solid routine for doing it.

You could use:

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

double *X, *Y;

int main()
{
   FILE *f = fopen("test.dat", "rt");
   char Line[256];
   unsigned int AllocSize = 0, Size = 0, n;

   if(!f)
   {
      fprintf(stderr, "Failed to open test.dat");
      return EXIT_FAILURE;
   }
   while(fgets(Line, sizeof(Line), f))
   {
      char *s = strtok(Line, ", ");
      if(s)
      {
         double x = strtod(s, 0);
         if((s = strtok(0, ",")) != 0)
         {
            double y = strtod(s, 0);
            if(Size >= AllocSize)
            {
               AllocSize += 128;
               X = realloc(X, AllocSize*sizeof(double));
               Y = realloc(Y, AllocSize*sizeof(double));
            }
            X[Size] = x;
            Y[Size] = y;
            Size++;
         }
         else
         {
            fprintf(stderr, "Wrong line in input");
         }
      }
      else
      {
         fprintf(stderr, "Wrong line in input");
      }
   }

   for(n = 0; n < Size; n++)
   {
      printf("%3u: %f %f\n", n, X[n], Y[n]);
   }
   free(X);
   free(Y);
   return EXIT_SUCCESS;
}

I C++ is an option it would be a lot easyer to do it with
ifstream and a vector

-- 
Absolutely not the best homepage on the net:
http://home20.inet.tele.dk/midgaard
But it's mine - Bertel

Bertel Brander wrote:
> I C++ is an option it would be a lot easyer to do it with
> ifstream and a vector

Just for your reference, this is the C++ version of the same program:

#include <vector>
#include <iostream>
#include <iomanip>
#include <fstream>

std::vector<double> X;
std::vector<double> Y;

int main()
{
   std::ifstream File("test.dat");
   if(!File)
   {
      std::cerr << "Failed to open test.dat" << std::endl;
      return 0;
   }
   double x, y;
   while(File >> x)
   {
      File.ignore(1024, ',');
      File >> y;
      X.push_back(x);
      Y.push_back(y);
   }
   for(std::vector<double>::size_type idx = 0; idx < X.size(); idx ++)
      std::cout << std::setw(3) << idx << ": " << X[idx] << " " << Y[idx] << std::endl;
}

-- 
Absolutely not the best homepage on the net:
http://home20.inet.tele.dk/midgaard
But it's mine - Bertel

In article <drjj8o$vuk$1@digitaldaemon.com>, Bertel Brander says...
>
>rvw wrote:
>> I am writing a command-line C program to perform cubic-pline interpolation on large data files.  Each line of the ASCII files will have: x-value,y-value.  The values will be converted to long doubles via _atold and then put into separate x-arrays and y-arrays.
>> 
>> I can probably eventually write code to properly input the data, but I am hoping someone already has a solid routine for doing it.
>
>You could use:
>
>#include <stdio.h>
>#include <stdlib.h>
>#include <string.h>
>
>double *X, *Y;
>
>int main()
>{
>    FILE *f = fopen("test.dat", "rt");
>    char Line[256];
>    unsigned int AllocSize = 0, Size = 0, n;
>
>    if(!f)
>    {
>       fprintf(stderr, "Failed to open test.dat");
>       return EXIT_FAILURE;
>    }
>    while(fgets(Line, sizeof(Line), f))
>    {
>       char *s = strtok(Line, ", ");
>       if(s)
>       {
>          double x = strtod(s, 0);
>          if((s = strtok(0, ",")) != 0)
>          {
>             double y = strtod(s, 0);
>             if(Size >= AllocSize)
>             {
>                AllocSize += 128;
>                X = realloc(X, AllocSize*sizeof(double));
>                Y = realloc(Y, AllocSize*sizeof(double));
>             }
>             X[Size] = x;
>             Y[Size] = y;
>             Size++;
>          }
>          else
>          {
>             fprintf(stderr, "Wrong line in input");
>          }
>       }
>       else
>       {
>          fprintf(stderr, "Wrong line in input");
>       }
>    }
>
>    for(n = 0; n < Size; n++)
>    {
>       printf("%3u: %f %f\n", n, X[n], Y[n]);
>    }
>    free(X);
>    free(Y);
>    return EXIT_SUCCESS;
>}
>
>I C++ is an option it would be a lot easyer to do it with ifstream and a vector
>
>-- 
>Absolutely not the best homepage on the net:
>http://home20.inet.tele.dk/midgaard
>But it's mine - Bertel


Bertel,

Much thanks!  I would have had a lot of trouble with memory allocation.  And I was going to implement the functionality of STRTOK() from scratch!

I will post my cubic-spline program after I have completed it.

Thanks again!

rvw