Thread: Reading from file and printing double data

Hi!

I am new to C and try to make a program that reads a segment of data from a file and prints it to the screen. When I declare the array that stores the data read from file as float, it works well. But when I declare it as double, the program prints out only zeros. Can anyone explain why? Am I doing something wrong?

I need to store this data with double precision because of computations that will be done with them later. How can I fix it?

Here is the code:

Code:

# include <stdio.h>

int main (void)
{
	FILE *fpIn = fopen( "S001.txt", "r");	// Open input file

	const int nsize = 2048;		
		
	double y[200000];

	if (fpIn != NULL) // Successful opening of input file
	{
	
		// Reads from input file first segment of nsize samples into y:	
		unsigned int i;			
		int numRead = 0;
		for (i = 0; i < nsize; i++ )
        	{
			numRead = fscanf(fpIn, "%f", &y[i]);

			printf("%f\n",y[i]);

         	}

		close(fpIn);			// Close input file
	}

	return 0;
}

Thank you in advance!

Elena

Thank you Tux0r! I followed your advice and tried an array of size 1 and %lf, but it still prints out 0.000000. It is very strange.

Code:

#include <stdio.h>

int main() {
	FILE *f=fopen("file.txt","r");

	if(f==NULL)
		return 1;

	double values[10];
	unsigned int i;			

	for(i = 0; i < 10; ++i) {
		fscanf(f, "%lf",&values[i]);
		printf("%lf\n",values[i]);
     }

	close(f);

	return 0;
}

file.txt

Code:

0.37
13.37
13.37
13.37
11.37
12.37
19.37
13.37
13.37
13.37

works here

Hurray! It worked!!! I just didn't put %lf on fscanf(), only on printf(), and when I did, it started to work! Thank you a lot, Tux0r!!!