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Date: Sun, 9 Jun 2002 19:39:18 +0300
From: Giorgos Keramidas <keramida@ceid.upatras.gr>
To: "Christopher J. Umina" <FJU@Fritzilldo.com>
Cc: FreeBSD Questions <questions@FreeBSD.ORG>
Subject: Re: Load Averages with C
Message-ID: <20020609163918.GB1595@hades.hell.gr>
References: <001201c20f54$46ba9e20$0301a8c0@uminafamily.com> <20020608222753.GA38586@hades.hell.gr> <001901c20fe2$9988cc60$0301a8c0@uminafamily.com>
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On 2002-06-09 11:22 -0700, Christopher J. Umina wrote:
> Why when I use getloadavg(3) do I come out with wierd numbers?
> 
> This is my code.
> 
> #include <stdio.h>
> #include <stdlib.h>
> 
> int main(void) {
>         int i;
>         double loadavg[3];
>         int getloadavg(double loadavg[], int nelem);

This is a prototype for getloadavg().  Since you included stdlib.h you
don't need this.

>         for (i = 0; i < 3; ++i) {
>                 printf ("%d\n", loadavg[i]);

You are using the values of the loadavg[] array without having first
called getloadavg().  Your printfs will output whatever random garbage
happens to be on the stack (where loadavg[] is allocated, since it's a
local variable of the main() function).

Try this:

	#include <stdio.h>
	#include <stdlib.h>

	int
	main(void) {
		int i;
		double loadavg[3];

		getloadavg(loadavg, 3);
		for (i = 0; i < 3; ++i) {
			printf (" %5.3lf", loadavg[i]);
		}
		printf("\n");
		return (0);
	}

Which seems to work nicely here:

	19:36 [charon@hades /tmp]$ cc -Wall -W orig.foo.c
	orig.foo.c: In function `main':
	orig.foo.c:10: warning: int format, double arg (arg 2)
	orig.foo.c:12: warning: control reaches end of non-void function
	19:36 [charon@hades /tmp]$ cc -Wall -W foo.c
	19:36 [charon@hades /tmp]$ ./a.out
	 1.663 1.466 0.970
	19:36 [charon@hades /tmp]$ ./a.out
	 1.663 1.466 0.970
	19:36 [charon@hades /tmp]$ ./a.out
	 1.663 1.466 0.970

- Giorgos


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