how to write a "long" value to a text file?

[skorch1]

I want to write that "mjd1" value to a text file. I tried it using fprinf() function. but it dint work.

#include<iostream.h>
#include<conio.h>
#include<dos.h>
#include<stdio.h>
void main()
{
   clrscr();
   FILE *TempFile; 
   int year,day,month,c=1,c1=0;
   char *temp="buf.txt";
   struct date d;
   long double mjd=54832,mjd1,count=0;
   cout<<"\nDay";
   cin>>day;
   cout<<"\nmonth";
   cin>>month;
   cout<<"\nyear";
   cin>>year;
   if(year!=2009)
   {
    for(int j=2009;j<year;j++)
    {   count+=365;
        if(j%4==0)
        c1++;
        cout<<"c1"<<c1;
    }
    }
   if(year%4==0)
   c+=2;
   else c+=3;
   cout<<"\nc2"<<c;
   for(int i=1;i<month;i++)
 
       { if(i==11) c++;
     if(i==4)  c++;
     if(i==6)   c++;
     if(i==9)   c++;
 
       count+=31;
     }
   cout<<"\n Count"<<count;
   cout<<endl;
   mjd1= count + day + mjd - c + c1;
   cout<<"\nModified Julian Date:"<<mjd1;
  TempFile=fopen(temp,"w+");
  fprintf(TempFile,"Modified Julian date%s\t\n",mjd1);
  fclose(TempFile);
  getch();
 
}
 

[donbock]

mjd1 is declared as a long double. Are you sure you didn't want it to be a long int? Review the man page for fprintf. The %s conversion specifier is only for use with strings. You need something different for long doubles; and something else again for long ints.

[Banfa]

Hi Don, IIRC there some weird and complex maths in calculation of julian dates that involves floating point operations. The output should be a long IIRC so mjd1 should cast to a unsigned(?) long for output.

However skorch1 you have used %s which indicates a pointer to a string, I wouldn't be surprised if this program caused a memory access violation. You need to cast mdj1 to unsiged long and use %lu in the fprintf format string and probably read up on format strings.

[donbock]

In my opinion, the definitive text for all date-related calculations is 'Calendrical Calculations' by Nachum Dershowitz and Edward Reingold. I have the first edition, copyrighted 1997. I see they are up to the 3rd edition now.