-----------------------------------

ihsh

Mon Sep 06, 2010 8:42 pm


Not being able to use pow()

-----------------------------------

It's me again.  :? 

I was trying to write the code of a binary converter. But I always got strange outputs so I tested my codes and found out that the problem was with the function pow ().
At first I thought it was a variable problem again, but it wasn't! I wrote a new program to test the function and the output was still zero. 

[code]
#include 
#include 

int main ()
{
	printf ("%d", pow(2,3));
	return (0);
}[/code]

Thanks for your time.


-----------------------------------

michaelp

Mon Sep 06, 2010 8:50 pm


RE:Not being able to use pow()

-----------------------------------

The format specifier "%d" is for an integer, but the function "pow" returns a double.
So, changing %d to %f will then print "8.000000" (or something similar). Changing that to "%.f" will then just print out 8.
Also, using %d, you can use:
[code]printf("%d", (int)pow(2, 3) );[/code]
And you will also get 8.
Here is a list of format specifiers in C:
http://www.mekong.net/tech/printf.htm

Also, when I compiled this using GCC, I got the [code]warning: format ?%d? expects type ?int?, but argument 2 has type ?double[/code]
Not sure if you got that when you compiled your code.


-----------------------------------

ihsh

Mon Sep 06, 2010 9:20 pm


RE:Not being able to use pow()

-----------------------------------

Thanks, program works now. :)
Also, when I compiled this using GCC, I got the
code:
warning: format ?%d? expects type ?int?, but argument 2 has type ?double

Not sure if you got that when you compiled your code.

No I didn't get any warning when compiling the code.


-----------------------------------

DtY

Tue Sep 07, 2010 3:41 pm


Re: RE:Not being able to use pow()

-----------------------------------

Also, when I compiled this using GCC, I got the I think that warning is only in pretty new versions of gcc.

e; Also, you should avoid using pow() unless the exponent rather large or a variable. a*a*a will be faster than pow(a,3).