Storing number in Hex format

[qazmlp]

I have to store the value of a 'long long' number in Hex format into a buffer.
What is the correct & best way of doing it so?

E.g.: If the number is: 374643194001883136, the stored value should be
0x0533000000000000
What I have currently is something like this:

long long Id = 374643194001883136LL ;
char IdInHexBuf[50]= {0} ;
sprintf( IdInHexBuf , "%#018llx" , Id ) ;

Any comments to improve this code?

[jacob navia]

"qazmlp" <qa********@rediffmail.com> a écrit dans le message de
news:db**************************@posting.google.c om...

I have to store the value of a 'long long' number in Hex format into a buffer. What is the correct & best way of doing it so?

E.g.: If the number is: 374643194001883136, the stored value should be
0x0533000000000000
What I have currently is something like this:

long long Id = 374643194001883136LL ;
char IdInHexBuf[50]= {0} ;
sprintf( IdInHexBuf , "%#018llx" , Id ) ;

Any comments to improve this code?

It is OK!

"If it ain't broken do not fix it!"

[Emmanuel Delahaye]

qazmlp wrote on 26/07/04 :

I have to store the value of a 'long long' number in Hex format into a
buffer. What I have currently is something like this:

long long Id = 374643194001883136LL ;
char IdInHexBuf[50]= {0} ;
sprintf( IdInHexBuf , "%#018llx" , Id ) ;

Any comments to improve this code?

- Be sure that <stdio.h> is included.
- The '= {0} ;' thing is useless but harmless.
- I'm not sure about the meaning of the '#' in the format string.
- "%llX" expects 'an unsigned long long'.
- Your spacing could be improved... (style-matter)

--
Emmanuel
The C-FAQ: http://www.eskimo.com/~scs/C-faq/faq.html

"C is a sharp tool"

[Erik de Castro Lopo]

qazmlp wrote:

I have to store the value of a 'long long' number in Hex format into a buffer.
What is the correct & best way of doing it so?

E.g.: If the number is: 374643194001883136, the stored value should be
0x0533000000000000

What I have currently is something like this:

long long Id = 374643194001883136LL ;
char IdInHexBuf[50]= {0} ;
sprintf( IdInHexBuf , "%#018llx" , Id ) ;

Any comments to improve this code?

In this case, using sprintf is OK, but normally you should
use snprintf:

snprintf ( IdInHexBuf , sizeof ( IdInHexBuf ), "%#018llx" , Id ) ;

which can prevent beuffer overflows.

Erik
--
+-----------------------------------------------------------+
Erik de Castro Lopo no****@mega-nerd.com (Yes it's valid)
+-----------------------------------------------------------+
"Indeed, I am impressed that Google runs an 8,000 node Linux
cluster, 5 data centers, an extensive network, and a rapidly
evolving application all with a staff of 12."
-- http://research.microsoft.com/~gray/...FAAMs_HPTS.doc

[Alan Balmer]

On Tue, 27 Jul 2004 07:51:24 +1000, Erik de Castro Lopo
<no****@mega-nerd.com> wrote:

qazmlp wrote:

I have to store the value of a 'long long' number in Hex format into a buffer.
What is the correct & best way of doing it so?

E.g.: If the number is: 374643194001883136, the stored value should be
0x0533000000000000

What I have currently is something like this:

long long Id = 374643194001883136LL ;
char IdInHexBuf[50]= {0} ;
sprintf( IdInHexBuf , "%#018llx" , Id ) ;

Any comments to improve this code?

In this case, using sprintf is OK, but normally you should
use snprintf:

snprintf ( IdInHexBuf , sizeof ( IdInHexBuf ), "%#018llx" , Id ) ;

which can prevent beuffer overflows.

Standard snprintf is new in C99, and may not be supported by the OP's
compiler.

--
Al Balmer
Balmer Consulting
re************************@att.net

[Emmanuel Delahaye]

Alan Balmer wrote on 27/07/04 :

long long Id = 374643194001883136LL ;

snprintf ( IdInHexBuf , sizeof ( IdInHexBuf ), "%#018llx" , Id ) ;

which can prevent beuffer overflows.

Standard snprintf is new in C99, and may not be supported by the OP's
compiler.

Huh! If the OP's compiler supports long long, chances are that it also
supports snprintf() that belongs to the same version of the definition
of the C-language.

--
Emmanuel
The C-FAQ: http://www.eskimo.com/~scs/C-faq/faq.html

"C is a sharp tool"

[Alan Balmer]

On Tue, 27 Jul 2004 00:57:31 +0200, Emmanuel Delahaye
<em***@YOURBRAnoos.fr> wrote:

Alan Balmer wrote on 27/07/04 :

long long Id = 374643194001883136LL ; snprintf ( IdInHexBuf , sizeof ( IdInHexBuf ), "%#018llx" , Id ) ;

which can prevent beuffer overflows.

Standard snprintf is new in C99, and may not be supported by the OP's
compiler.

Huh! If the OP's compiler supports long long, chances are that it also
supports snprintf() that belongs to the same version of the definition
of the C-language.

There might be a statistical correlation, but no logical one.

--
Al Balmer
Balmer Consulting
re************************@att.net

[Keith Thompson]

Emmanuel Delahaye <em***@YOURBRAnoos.fr> writes:

Alan Balmer wrote on 27/07/04 :

long long Id = 374643194001883136LL ; snprintf ( IdInHexBuf , sizeof ( IdInHexBuf ), "%#018llx" , Id ) ;
which can prevent beuffer overflows.

Standard snprintf is new in C99, and may not be supported by the OP's
compiler.

Huh! If the OP's compiler supports long long, chances are that it also
supports snprintf() that belongs to the same version of the definition
of the C-language.

Possibly, but I wouldn't bet on it. Many pre-C99 compilers support
long long; the committee added it to C99 because it was existing
practice. The snprintf() function is almost certainly provided by the
C library, not by the compiler, and they're not necessarily in sync.

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Emmanuel Delahaye]

Alan Balmer wrote on 27/07/04 :

On Tue, 27 Jul 2004 00:57:31 +0200, Emmanuel Delahaye
<em***@YOURBRAnoos.fr> wrote:

Alan Balmer wrote on 27/07/04 :

Standard snprintf is new in C99, and may not be supported by the OP's
compiler.

Huh! If the OP's compiler supports long long, chances are that it also
supports snprintf() that belongs to the same version of the definition
of the C-language.

There might be a statistical correlation, but no logical one.

Come on...

--
Emmanuel
The C-FAQ: http://www.eskimo.com/~scs/C-faq/faq.html

"C is a sharp tool"

[Keith Thompson]

Emmanuel Delahaye <em***@YOURBRAnoos.fr> writes:

Alan Balmer wrote on 27/07/04 :

On Tue, 27 Jul 2004 00:57:31 +0200, Emmanuel Delahaye
<em***@YOURBRAnoos.fr> wrote:

Alan Balmer wrote on 27/07/04 :
Standard snprintf is new in C99, and may not be supported by the OP's
compiler.
Huh! If the OP's compiler supports long long, chances are that it
also supports snprintf() that belongs to the same version of the
definition of the C-language.

There might be a statistical correlation, but no logical one.

Come on...

Perhaps you could expand on that. (See my response elsethread.)

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Daniel Haude]

On Mon, 26 Jul 2004 15:23:21 -0700,
Alan Balmer <al******@att.net> wrote
in Msg. <o0********************************@4ax.com>

On Tue, 27 Jul 2004 07:51:24 +1000, Erik de Castro Lopo
<no****@mega-nerd.com> wrote:

qazmlp wrote:

I have to store the value of a 'long long' number in Hex format into a buffer.
What is the correct & best way of doing it so?

E.g.: If the number is: 374643194001883136, the stored value should be
0x0533000000000000

What I have currently is something like this:

long long Id = 374643194001883136LL ;
char IdInHexBuf[50]= {0} ;
sprintf( IdInHexBuf , "%#018llx" , Id ) ;

Any comments to improve this code?

In this case, using sprintf is OK, but normally you should
use snprintf:

snprintf ( IdInHexBuf , sizeof ( IdInHexBuf ), "%#018llx" , Id ) ;

which can prevent beuffer overflows.

Standard snprintf is new in C99, and may not be supported by the OP's
compiler.

Supported or not; it's important to notice that that sprintf() call it a
buffer overflow waiting to happen. Sure, 50 is an awful lot of digits,
but who knows how long a "long long" will be in 20 years?

Although it's unlikely that this program will be re-compiled in 20
years, potential buffer overflows are something to be very aware of, and
sprintf calls like this one should either be replaced by snprintf, or,
if that is unavailable, by some check for the size of the number to be
sprintfed.

--Daniel

--
"With me is nothing wrong! And with you?" (from r.a.m.p)