atof()

atof()

[Reinaldo Nolasco Sanches]

I have a problem with atof()... and I don't understand because it...
When I use atof() to get a value of a string... and put in my double var, the value is not the
same...

I make a little example...

#include <stdio.h>

int main()
{
	double teste;
	char   strteste[10];
	
	strcpy( strteste, "120.1" );
	
	teste = atof( strteste );
	
	printf( "\n\tResult is = %.2f\n\n", teste );
	
	return 0;
}

and the result is this

    Result is = 1078984704.00

and I don't understand this... I make this in several PCs... and in a SuSE, in a Slackware and in
a RedHat(urgg!), and in all the erro ocurred...

I don't know if I need set a specific #define... or a specific environment var...

Please... anybody can help me ???

I compiled with...
   gcc -i teste.c -o teste


Thanks a lot in advance...




=====
"When you know Slackware, you know Linux... when you know Red Hat, all you know is Red hat"

- Anyone seen smoking will be assumed to be on fire and will be summarily put out.
- Power doesn't corrupt people, people corrupt power.

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Re: atof()

[H. J. Lu]

On Mon, Aug 19, 2002 at 10:49:53AM -0700, Reinaldo Nolasco Sanches wrote:
> 
> I have a problem with atof()... and I don't understand because it...
> When I use atof() to get a value of a string... and put in my double var, the value is not the
> same...
> 
> I make a little example...
> 
> #include <stdio.h>

You need

#include <stdlib.h>

to get the prototype of atof.

> 
> int main()
> {
> 	double teste;
> 	char   strteste[10];
> 	
> 	strcpy( strteste, "120.1" );
> 	
> 	teste = atof( strteste );
> 	
> 	printf( "\n\tResult is = %.2f\n\n", teste );
> 	
> 	return 0;
> }
> 
> and the result is this
> 
>     Result is = 1078984704.00
> 
> and I don't understand this... I make this in several PCs... and in a SuSE, in a Slackware and in
> a RedHat(urgg!), and in all the erro ocurred...
> 
> I don't know if I need set a specific #define... or a specific environment var...
> 
> Please... anybody can help me ???
> 


H.J.

Re: atof()

[Janis Johnson]

On Mon, Aug 19, 2002 at 10:49:53AM -0700, Reinaldo Nolasco Sanches wrote:
> 
> I have a problem with atof()... and I don't understand because it...
> When I use atof() to get a value of a string... and put in my double var, the value is not the
> same...
> 
> I make a little example...
> 
> #include <stdio.h>
> 
> int main()
> {
> 	double teste;
> 	char   strteste[10];
> 	
> 	strcpy( strteste, "120.1" );
> 	
> 	teste = atof( strteste );
> 	
> 	printf( "\n\tResult is = %.2f\n\n", teste );
> 	
> 	return 0;
> }
> 
> and the result is this
> 
>     Result is = 1078984704.00
> 

This mailing list is for questions about developing GCC, not about
using it.

A hint, though: try compiling with -Wall to turn on more warnings.

Janis

Re: atof()

[Andreas Jaeger]

Reinaldo Nolasco Sanches <r_linux@yahoo.com> writes:

> I have a problem with atof()... and I don't understand because it...

This is the wrong group for such kind of questions.  I guess this
might be even answered in the C FAQ or a good C book.

If you compile your program with warnings enabled, you'll get:
$ gcc -Wall t.c
t.c: In function `main':
t.c:10: warning: implicit declaration of function `atof'

Without a prototype the function is declared as returning int instead
of doubles.

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj

Re: atof()

[Brad House]

#include <stdlib.h> needs to be added.  The default
data type for an undeclared function is int which
will cause oddities like that.  Always compile
with -Wall when debugging stuff, as it will
report such errors.

-Brad

Reinaldo Nolasco Sanches wrote:

Re: atof()

[Erik Trulsson]

On Mon, Aug 19, 2002 at 10:49:53AM -0700, Reinaldo Nolasco Sanches wrote:
> 
> I have a problem with atof()... and I don't understand because it...
> When I use atof() to get a value of a string... and put in my double var, the value is not the
> same...

This is not the right list for this kind of question but I will answer
anyway.  (This list is for discussion of the development of gcc, not
how to use gcc.)

If you use atof() you need to include stdlib.h first to get the
prototype.  Otherwise the compiler will assume atof() returns an int
and thus generate bad code.

> 
> I make a little example...
> 
> #include <stdio.h>
> 
> int main()
> {


-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013@student.uu.se

Re: atof()

[Reinaldo Nolasco Sanches]

Thanks a lot to all helps...

And very very sorry for my stupid question of std C in gcc mainlist...


:)


Thanks.. :)




=====
"When you know Slackware, you know Linux... when you know Red Hat, all you know is Red hat"

- Anyone seen smoking will be assumed to be on fire and will be summarily put out.
- Power doesn't corrupt people, people corrupt power.

- r_linux@yahoo.com -- http://slackware.linuxbr.org
- UIN: 42853394 - irc.brasnet.org(#slackware)

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