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c++.command-line - Inputting comma-delimited data

reply rvw <rvw_member pathlink.com> writes:
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
Jan 29 2006
next sibling parent Jan Knepper <jan smartsoft.us> writes:
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?


-- 
ManiaC++
Jan Knepper

But as for me and my household, we shall use Mozilla...
www.mozilla.org
Jan 29 2006
prev sibling parent reply Bertel Brander <bertel post4.tele.dk> writes:
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
Jan 29 2006
next sibling parent Bertel Brander <bertel post4.tele.dk> writes:
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
Jan 29 2006
prev sibling parent rvw <rvw_member pathlink.com> writes:
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
Jan 30 2006