Formatted IO iostream/stdio
I am trying to read a large, random data file with mixed data types and formats. I can use the c++ fscanf to harvest the information, but it seems like it is having problems with the read. Doubles are not getting the right values. The numbers are in large scientific format. I can't imagine that this has not been done before, but I am having a hard time finding it. The columns are fixed, but the numbers can shift inside of them and are somtimes missing. I need to be able to read a fixed width of characters and convert them to a number and store them. If it is not a number, I need to return 0. The resulting stream needs to be pointed to the next section. Is there an equivalent to the ostream << setw(int) for the istream? If so how do I use it?
I have been trying to use fscanf functions with a ifstream, but it fails, due to an incomatibility. How to I convert an istream& to a FILE *?
Any help would be appreciated.
Thanks,
Xydqyv
[994 byte] By [
Xydqyv] at [2007-11-18 13:38:37]
# 2 Re: Formatted IO iostream/stdio
Here is the code:
-----------
#include <stdio.h>
#include <iostream.h>
#include <fstream.h>
int main (){
FILE *cfIn, *cfOut;
ifstream in;
ofstream out;
long node=0, a=0, b=0;
double x=0,y=0,z=0;
char buffer[255];
in.open("test.data");
out.open("test.data.out");
in.close();
out.close();
while(!in.eof()){
in.getline(buffer,255);
}
if ((cfIn = fopen("test.data","r"))==NULL)
{ cout<< "Read not opened" <<endl<<flush; return(1);}
if ((cfOut = fopen("test.data.out","w"))==NULL)
{ cout<< "Write file not opened" <<endl<<flush; return(1);}
while(!feof(cfIn)){
fscanf(cfIn,"%d%d%d%E%E%E",&node,&a,&b,&x,&y,&z);
cout << "Read "<<node<< " "<<a<<" "<<b<<" "<<x<<" "<<y<<" "<<z<<" "<<&cfIn<<&(cfIn[1])<<endl<<flush;
fprintf(cfOut,"%8d|%8d|%8d|%16.9e|%16.9e|%16.9e\n",node,a,b,x,y,z);
}
return(0);
}
-----------
The sample input is something like this:
20165 0 0 8.54950813 1.319062213e-02 6.25854926
20166 0 0 8.53367443 2.940708302e-02 6.25480276
20167 0 0 8.74123004 3.641833084e-02 6.43496717
20168 0 0 8.75848943 3.239500379e-02 6.48667214
20169 0 0 8.88847866 0.172800315 6.89416161
20170 0 0 8.38000417 0.00000000 4.93453979
20171 0 0 8.40150208 -1.076254991e-12 4.93454502
20172 0 0 8.38000599 0.00000000 5.01637419
20173 0 0 8.38000781 0.00000000 5.09820859
20174 0 0 8.40148231 0.00000000 5.09821251
- I need the double precision for the numbers, but what is the format character for a double? I figured out that I am having a problem with data types on the read. I would sill like to be able to use scanf on iostream objects though if anyone knows how to manage that.
Thanks for the quick response ;-)
