CODEWITHSUNDEEP
c
Dalek
Dalek

Reputation: 4318

How could I read a file with two columns in two arrays?

I wrote this function in C which import a two column file in two arrays and then finds the linear interpolation between two successive points if the input value of the function lies between them.

double Prevot_redden(double wave, double Av)
{
 int  i,j; 
 const double Rv = 2.75;  /* Set by Prevot */ 
 double       micron, r = 0.;
 micron = wave * 1e6;  /* convert to micron */
 /*Prevot reddening counters*/
 int raw_prevot_size=4002;
 /*data array for raw Prevot reddening */
 double *raw_prevot_wave_data,*raw_prevot_data;
 /*allocate space for raw Prevot reddening*/
 raw_prevot_wave_data=(double *)calloc(raw_prevot_size,sizeof(double *));
 raw_prevot_data=(double *)calloc(raw_prevot_size,sizeof(double *));
 /*reading a file*/
 char *f_prevot=fopen("SMC_prevot.dat","r");
 if (f_prevot==NULL ) 
 {
        fprintf(stderr,"Can not open reddening file !\n");
        exit(-1);
 }
 for (i=0;i<raw_prevot_size;i++)
 {
   sscanf(f_prevot,"%lf %lf",&raw_prevot_wave_data[i],&raw_prevot_data[i]);/*Wavelength and E(lambda-V)/E(B-V)*/
   /* convert to micron */
   raw_prevot_wave_data[i]*=1e-4;
 }

  for (j = 0; j < raw_prevot_size-2; j++)
  {
      if ((micron>raw_prevot_wave_data[j]) &&(micron<=raw_prevot_wave_data[j+1]))
      {

       r= lininterp(raw_prevot_wave_data[j],
                       raw_prevot_wave_data[j+1],
                       raw_prevot_data[j],
                       raw_prevot_data[j+1],
                       micron);
      }
  }
  r *= Av;
  r /= Rv;
  r /= -2.5;
  r  = pow(10, r);
  return(r);
}

When I compile the code, for the line with the command fopen, I get this warning message. Can somebody explain what the reason is for the message?!!

In function 'Prevot_redden':
14: warning: initialization from incompatible pointer type

Upvotes: 1

Views: 255

Answers (3)

Oleg Razgulyaev
Oleg Razgulyaev

Reputation: 5935

char *f_prevot=fopen("SMC_prevot.dat","r");

fopen() returns FILE*, not char*

Upvotes: 0

CapelliC
CapelliC

Reputation: 60014

you need 

FILE *f_prevot=fopen("SMC_prevot.dat","r");
·..

if (fscanf(f_prevot,"%lf %lf",&raw_prevot_wave_data[i],&raw_prevot_data[i]) == 2)
...
fclose(f_prevot);

Upvotes: 1

Sridutt
Sridutt

Reputation: 382

FILE *f_prevot=fopen("SMC_prevot.dat","r");

would be my first try as fopen returns a pointer of FILE * type

Upvotes: 0

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