Something About Date Type

[Donkey]

Hello, I want to find out how many digits does each date type have and
how many bytes does it occupy in memory, so I wrote a program below:

#include <stdio.h>
const long double num=1123222.232 121342;
main()
{
Printf("the number occupies: %i, and it is 1123222.2321213 42
\n",sizeof num);
printf("char: %i ,the number is %c\n",sizeof(ch ar),(char)num);
printf("widecha r: %i\n",sizeof(wc har_t));
printf("singed char: %i\n",sizeof(si gned char));
printf("unsigne d char: %i\n",sizeof(un signed char));
printf("int: %i, the number is %i\n",sizeof(in t),(int)num);
printf("long int: %i, the number is %li\n",sizeof(l ong int),(long
int)num);
printf("float: %i, the number is %f\n", sizeof(float),f loat(num));
printf("double: %i, the number is
%lf\n",sizeof(d ouble),(double) num);
printf("long double: %i,the number is %Lf\n",sizeof(l ong
double),(long double)num);
printf("long long int: %i\n",sizeof(lo ng long int));
printf("long long double: %i\n",sizeof(lo ng long double));
}

But the execution result of the program is very surprising:

the number occupies: 12, and it is 1123222.2321213 42
char: 1 ,the number is 
widechar: 2
singed char: 1
unsigned char: 1
int: 4, the number is 1123222
long int: 4, the number is 1123222
float: 4, the number is 1123222.250000
double: 8, the number is 1123222.232121
long double: 12,the number is -0.000000
long long int: 8
long long double: 8

You may notice that:
the memory occupied by int Date type and long int Date type is the
same,
print of long double number is not correct ,
and the memory long long double date type occupied is smaller (8 bytes)
than long double date type(12 bytes).
The Compiler I Use is GCC. The OS I use is Windows XP.
Can anyone tells me why do these problems happen?
Thanks a million.

[Jonathan Burd]

Re: Something About Date Type

Donkey wrote:[color=blue]
> Hello, I want to find out how many digits does each date type have and
> how many bytes does it occupy in memory, so I wrote a program below:
>[/color]

Which ``date'' type are you talking about?
[color=blue]
> #include <stdio.h>
> const long double num=1123222.232 121342;
> main()[/color]

int main (void) or
int main (int argc, char *argv[]) or
int main (int argc, char **argv).

Please read the newsgroup archive before posting code.
[color=blue]
> {
> Printf("the number occupies: %i, and it is 1123222.2321213 42
> \n",sizeof num);[/color]

Identifiers in C are case-sensitive. ``Printf'' is not the same as
``printf''
[color=blue]
> printf("char: %i ,the number is %c\n",sizeof(ch ar),(char)num);[/color]

Loss of data. Why print a double value as a char?
sizeof evaluates to a value of type size_t. You can use
a cast to ``unsigned long'' here and %lu for the conversion
specifier.
[color=blue]
> printf("widecha r: %i\n",sizeof(wc har_t));
> printf("singed char: %i\n",sizeof(si gned char));
> printf("unsigne d char: %i\n",sizeof(un signed char));
> printf("int: %i, the number is %i\n",sizeof(in t),(int)num);
> printf("long int: %i, the number is %li\n",sizeof(l ong int),(long
> int)num);
> printf("float: %i, the number is %f\n", sizeof(float),f loat(num));
> printf("double: %i, the number is
> %lf\n",sizeof(d ouble),(double) num);
> printf("long double: %i,the number is %Lf\n",sizeof(l ong
> double),(long double)num);
> printf("long long int: %i\n",sizeof(lo ng long int));
> printf("long long double: %i\n",sizeof(lo ng long double));
> }[/color]

main returns int.
[color=blue]
>
> But the execution result of the program is very surprising:[/color]

Not really surprising.

<snip>
[color=blue]
>
> You may notice that:
> the memory occupied by int Date type and long int Date type is the
> same,[/color]

Again, which ``Date'' type? I don't see any such type in your code.

<snip>
[color=blue]
> Can anyone tells me why do these problems happen?
> Thanks a million.
>[/color]

They happen because you forget to read a good book on C.
Pick up K&R 2. :)


Regards,
Jonathan.

--
Meow!

[Keith Thompson]

Re: Something About Date Type

"Donkey" <newsdonkey@hot mail.com> writes:[color=blue]
> Hello, I want to find out how many digits does each date type have and
> how many bytes does it occupy in memory, so I wrote a program below:
>
> #include <stdio.h>
> const long double num=1123222.232 121342;
> main()[/color]

This should be "int main(void)".
[color=blue]
> {
> Printf("the number occupies: %i, and it is 1123222.2321213 42\n",sizeof num);[/color]

printf, not Printf.

The "%i" format expects an int. sizeof yields a size_t.

To print the result of sizeof, convert it to unsigned long -- or use
"%zu" if your runtime library supports it (it's new in C99). For
example:

printf("sizeof num = %ld\n", (unsigned long)sizeof num);
[color=blue]
> printf("char: %i ,the number is %c\n",sizeof(ch ar),(char)num);
> printf("widecha r: %i\n",sizeof(wc har_t));
> printf("singed char: %i\n",sizeof(si gned char));
> printf("unsigne d char: %i\n",sizeof(un signed char));
> printf("int: %i, the number is %i\n",sizeof(in t),(int)num);
> printf("long int: %i, the number is %li\n",sizeof(l ong int),(long int)num);
> printf("float: %i, the number is %f\n", sizeof(float),f loat(num));[/color]

float(num) is a syntax error; you mean (float)num.
[color=blue]
> printf("double: %i, the number is %lf\n",sizeof(d ouble),(double) num);
> printf("long double: %i,the number is %Lf\n",sizeof(l ong double),(long double)num);
> printf("long long int: %i\n",sizeof(lo ng long int));
> printf("long long double: %i\n",sizeof(lo ng long double));[/color]

There is no "long long double" in standard C.
[color=blue]
> }[/color]

The code you posted isn't the code you compiled (unless your compiler
is entirely too forgiving). It would also be helpful if you kept your
line length down.
[color=blue]
> But the execution result of the program is very surprising:
>
> the number occupies: 12, and it is 1123222.2321213 42
> char: 1 ,the number is 
> widechar: 2
> singed char: 1
> unsigned char: 1
> int: 4, the number is 1123222
> long int: 4, the number is 1123222
> float: 4, the number is 1123222.250000
> double: 8, the number is 1123222.232121
> long double: 12,the number is -0.000000
> long long int: 8
> long long double: 8
>
> You may notice that:
> the memory occupied by int Date type and long int Date type is the
> same,
> print of long double number is not correct ,
> and the memory long long double date type occupied is smaller (8 bytes)
> than long double date type(12 bytes).
> The Compiler I Use is GCC. The OS I use is Windows XP.[/color]

It's not uncommon for types int and long int to be the same size.

Possibly your runtime library (which is separate from your compiler)
doesn't handle "%Lf" properly.

Recent versions of gcc properly reject "long long double". A buggy
old version treats it as "long long".

--
Keith Thompson (The_Other_Keit h) kst-u@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.

[Keith Thompson]

Re: Something About Date Type

Jonathan Burd <jb@nomail.co m> writes:[color=blue]
> Donkey wrote:[color=green]
>> Hello, I want to find out how many digits does each date type have and
>> how many bytes does it occupy in memory, so I wrote a program below:[/color]
>
> Which ``date'' type are you talking about?[/color]

Perhaps it was a typo for "data type".

--
Keith Thompson (The_Other_Keit h) kst-u@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.

[Peter Shaggy Haywood]

Re: Something About Date Type

Groovy hepcat Keith Thompson was jivin' on Fri, 31 Mar 2006 06:17:34
GMT in comp.lang.c.
Re: Something About Date Type's a cool scene! Dig it!
[color=blue]
>To print the result of sizeof, convert it to unsigned long -- or use
>"%zu" if your runtime library supports it (it's new in C99). For
>example:
>
> printf("sizeof num = %ld\n", (unsigned long)sizeof num);[/color]

No doubt Keith means this. (Note the %lu conversion specifier):

printf("sizeof num = %lu\n", (unsigned long)sizeof num);

--

Dig the even newer still, yet more improved, sig!

http://alphalink.com.au/~phaywood/

"Ain't I'm a dog?" - Ronny Self, Ain't I'm a Dog, written by G. Sherry & W. Walker.
I know it's not "technicall y correct" English; but since when was rock & roll "technicall y correct"?

[Keith Thompson]

Re: Something About Date Type

phaywood@alphal ink.com.au.NO.S PAM (Peter "Shaggy" Haywood) writes:[color=blue]
> Groovy hepcat Keith Thompson was jivin' on Fri, 31 Mar 2006 06:17:34
> GMT in comp.lang.c.
> Re: Something About Date Type's a cool scene! Dig it!
>[color=green]
>>To print the result of sizeof, convert it to unsigned long -- or use
>>"%zu" if your runtime library supports it (it's new in C99). For
>>example:
>>
>> printf("sizeof num = %ld\n", (unsigned long)sizeof num);[/color]
>
> No doubt Keith means this. (Note the %lu conversion specifier):
>
> printf("sizeof num = %lu\n", (unsigned long)sizeof num);[/color]

Yes, thanks for the correction.

--
Keith Thompson (The_Other_Keit h) kst-u@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.