The fscanf function is just like the scanf function,
except that the first argument of fscanf specifies a stream from
which to read, whereas scanf can only read from standard input.
Here is a code example that generates a text file containing five
numbers with fprintf, then reads them back in with fscanf.
Note the use of the # flags in the %#d conversions in the
fprintf call; this is a good way to generate data in a format
that scanf and related functions can easily read with the
%i input conversion.
#include <stdio.h>
#include <errno.h>
int main()
{
float f1, f2;
int i1, i2;
FILE *my_stream;
char my_filename[] = "snazzyjazz.txt";
my_stream = fopen (my_filename, "w");
fprintf (my_stream, "%f %f %#d %#d", 23.5, -12e6, 100, 5);
/* Close stream; skip error-checking for brevity of example */
fclose (my_stream);
my_stream = fopen (my_filename, "r");
fscanf (my_stream, "%f %f %i %i", &f1, &f2, &i1, &i2);
/* Close stream; skip error-checking for brevity of example */
fclose (my_stream);
printf ("Float 1 = %f\n", f1);
printf ("Float 2 = %f\n", f2);
printf ("Integer 1 = %d\n", i1);
printf ("Integer 2 = %d\n", i2);
return 0;
}
This code example prints the following output on the screen:
