Reading text file twice, can it be done once?

I am reading a text file of two-column numeric data. I do not know the number of rows that the file will contain. Currently, I read the file twice: Once to ascertain the length and the second time to fill the arrays with the data. Is there a way to create and populate the arrays while only having to read the text file once?

Here is my current code:

Code:

FILE* fid;
double tempx, tempy;

fid = fopen("c:/file.txt","rt");
int i=0;
while( fscanf(fid,"%le%le", &tempx, &tempy )!= EOF )
	i++;
rewind( fid );

x = new double[i];
y = new double[i];

i=0;
while (fscanf(fid,"%le%le", x+i, y+i)!= EOF)
	i++;
fclose(fid);

Thanks for your time.

Code:

x = new double;

That's C++.

If you're using C, go with realloc().

Good point, I really should have posted this in c++, but I was hesitant, because I wanted to stick with C file handling rather than c++ file handling.

I'll move the post to the c++ board.