C integer type Size

**[guard]** · 09-26-2002

ok, im working on a program for class that takes int types in c and tells you the range and size

here is my code, but i get like 40 errors, and the compiler is pointing to the "{" at the begining of the RANGE function. can someone help me out here, im not see the error!

#include <stdio.h>

void RANGE(type, name)
{
type minval, maxval, bit;
unsigned bits;
char *format;

bits=1; bit=1;
while (bit<<=1)
{
bits++;
}

if ((type)(1L<<(bits-1))>0)
{
format="%12lu";
minval=(type)0;
}
else
{
format="%12ld";
minval=(type)(1L<<(bits-1));
}

maxval=minval-1;

printf("%20s (%2u bits): ", name, bits);
printf(format, (long) minval);
printf(" to ");
printf(format, (long) maxval);
printf("\n");
}

void main()
{
printf("\nTesting Range of Unsigned Ints... \n\n");
RANGE(unsigned char, "unsigned char");
RANGE(unsigned short int, "unsigned short int");
RANGE(unsigned int, "unsigned int");
RANGE(unsigned long int, "unsigned long int");

printf("\nTesting Range of Signed Ints... \n\n");
RANGE(signed char, "signed char");
RANGE(signed short int, "signed short int");
RANGE(signed int, "signed int");
RANGE(signed long int, "signed long int");
}

**Cshot** · 09-26-2002

Wow, this code is filled so many errors I dunno if I'd wanna touch this with my 10 foot pole.

Here's a few comments:
- use code tags
- use int main, not void main
- void RANGE(type, name), you didn't specify a type for type or name
- type minval, maxval, bit; what's type?
- unsigned bits; again, what type is this?
.
.
.
My initial reaction is I wouldn't want to do this program this way. Oh man, anyone wanna tackle this?

**Shiro** · 09-26-2002

Not quite sure what you're doing. But you perhaps can use this:

sizeof (type) - gives the size of type in bytes

Fill the variable of type with ones and you have the range of that type.

**quzah** · 09-26-2002

Your whole problem stems from this:

void main()

Ok, maybe not, but that's something you should never do. Anyone who tells you to do that should have their kneecaps broken.

Your whole problem stems from this:

void RANGE(type, name)

Didn't I just say that? Anyway, this time it's true. 'type' is not a valid type. 'name' isn't either. You have to actually specify types for your variables. You can't just declare generic non-types there. That's wrong. You'll have to actually specify the types. In other words, you'll have to redo your thought process here.

[edit]Damn. Multiple people beat me to it.[/edit]
[edit]
Personally, I'd do this:

Use a switch, have them enter a single character which represents the type you want to test, then hard code the test.
[/edit]

Quzah.

**[guard]** · 09-26-2002

see, the problem is, this is the code my prof gave me

and i dont know what its doing either
i THINK that in class he had it as a large define statement instead of a function, but then he changed it to this

im so lost!

**Cshot** · 09-26-2002

>> see, the problem is, this is the code my prof gave me
I am quite surprised. How did these guys become professors anyways?

Just code it the way quzah suggested and you'll be fine.

**[guard]** · 09-26-2002

ok, i got the code to work, so if any of you would tryed to suggest help wants to see what its actually supposed to do, here it is

#include <stdio.h>

#define RANGE(type, name) \
{ \
type minval, maxval, bit ; \
unsigned bits ; \
char *format ; \
\
/* Measure size of data type */ \
bits = 1 ; bit = (type) 1 ; \
while (bit <<= 1) bits++ ; \
\
/* Signed or unsigned? (2's complement!) */ \
if ((type) (1L << (bits - 1)) > 0) \
{ \
format = "%12lu" ; /* unsigned */ \
minval = (type) 0 ; \
} \
else \
{ \
format = "%12ld" ; /* signed */ \
minval = (type) 1 << (bits - 1) ; \
} \
\
/* Assume two's complement */ \
maxval = minval - 1 ; \
\
printf("%20s (%2u bits): ", name, bits) ; \
printf(format, (long) minval) ; \
printf(" to ") ; \
printf(format, (long) maxval) ; \
printf("\n") ; \
}

int main()
{
printf("\nTesting range of UNSIGNED ints ...\n\n") ;
RANGE(unsigned char, "unsigned char" ) ;
RANGE(unsigned short int, "unsigned short int" ) ;
RANGE(unsigned int, "unsigned int" ) ;
RANGE(unsigned long int, "unsigned long int" ) ;

printf("\nTesting range of SIGNED ints ...\n\n") ;
RANGE(signed char, "signed char" ) ;
RANGE(signed short int, "signed short int" ) ;
RANGE(signed int, "signed int" ) ;
RANGE(signed long int, "signed long int" ) ;

return 0 ;
}

now, i have to change the #DEFINE to a function... shoot me!

-[guard]
ps: thanks for the help all

**quzah** · 09-26-2002

Originally posted by [guard]
see, the problem is, this is the code my prof gave me

and i dont know what its doing either
i THINK that in class he had it as a large define statement instead of a function, but then he changed it to this

im so lost!

Maybe he's tired, or drunk. A #define statement could possibly work. I just don't see the point.

Code:

int type;

printf("Pick a type by choosing the correct number:\n"
	"1 - signed char\n"
	"2 - unsigned char\n"
	"3 - signed short int\n"
	"4 - unsigned short int\n"
	"5 - signed long int\n"
	"6 - unsigned long int\n"
	"Your choice: " );

if( scanf("%d", &type ) == 1 )
{
	switch( type )
	{
		case 1: ... do calculation; break;
	}
}
else
	printf("Input failure. Terminating.\n");

Quzah.

**Hammer** · 09-26-2002

Here's a few comments:
- use code tags

... and if you don't know how, see the link in my signature.

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