Loading data into a dynamic array

Hi!

I am reading data from a text file into a dynamically constructed array, like this:

Code:

---

static const unsigned pN = 1 << 13;

float *p = NULL;
p = new float[ pN ];

// DATA
FILE *file;

file = fopen( "dist.txt" , "r" );

unsigned int i = 0;

while( !feof(file) ) {
    fscanf( file, "%f", p[ i ] );
    i++;
}

fclose(file);

---

This works fine for arrays of float but does not work when I change the type to double? Any idea why, and how to fix it?

Thanks for you help!
Serge

Are you also changing %f to %lf to indicate that you mean double?

--
Mats

Quote:

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Originally Posted by serge

This works fine

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No, it doesn't work at all.

Code:

---

float arrp[ pN ];

---

What's the purpose of this line? With doubles it takes twice the amount of stack memory and it is obviously two much - the stack is just a few megabytes for your program.

BTW, in C++ you'd use std::vector to avoiding a) overallocating way too much, b) still running out of bounds in the file has more data than that.

Quote:

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Originally Posted by matsp

Are you also changing %f to %lf to indicate that you mean double?

--
Mats

---

Thanks! This fixed the problem in fscanf.

BTW: What is the difference between %f and %lf in printf?

Quote:

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Originally Posted by anon

Code:

---

float arrp[ pN ];

---

What's the purpose of this line? With doubles it takes twice the amount of stack memory and it is obviously two much - the stack is just a few megabytes for your program.

BTW, in C++ you'd use std::vector to avoiding a) overallocating way too much, b) still running out of bounds in the file has more data than that.

---

Sorry for the confusion, this line was superflous, just deleted it in edit

Quote:

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Originally Posted by serge

Thanks! This fixed the problem in fscanf.

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And yet the code you posted is still wrong. That isn't the real code, is it?

Quote:

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Originally Posted by brewbuck

And yet the code you posted is still wrong. That isn't the real code, is it?

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ok, here is code that works

Code:

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#include <iostream>

int main()
{
static const unsigned N = 13;
static const unsigned pN = 1 << N;

double *p = NULL;
p = new double[ pN ];

unsigned int i;

FILE *file;
file = fopen( "dist.txt" , "r" );

i = 0;

while( !feof(file) ) {
    fscanf( file, "%lf", &p[ i ] );
    i++;
}
fclose(file);

system( "PAUSE" );
return 0;
}

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Why it's bad to use feof() in a control loop.

Quote:

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Originally Posted by serge

ok, here is code that works

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And the missing '&' appears!