Hi, can somebody help me out with a better version of the following
functions which only convert decimal integer to it's corresponding
binary form. the
problem i'm having now is that I can't figure out how to handle when 0
is
passed as parameter in only one function, my code below have to add
one more function to handle this situation, any help is appreciated,
thanx.
char *Dec2Bin(const int decimal) {
char *binary=new char[64];
int dividend,i;
dividend=decimal;
for(i=0;dividend!=0;++i) {
binary[i]=(dividend&1)+'0'; // (a % b) == (a & (b-1))
dividend>>=1;
}
binary[i]='\0';
return strrev(binary);
}
char *Decimal2Binary(const int decimal) {
return (decimal==0)?"0":Dec2Bin(decimal);
} 20 1819
Emmanuel Delahaye wrote: In 'comp.lang.c', ru****@sohu.com (sugaray) wrote:
char *binary=new char[64];
There is no 'new' in C.
It's a perfectly valid identifier name (albeit used in a rather strange and
syntactically erroneous manner in the code you quote here). In fact, I
often use it myself in code such as:
FOO *prefix_CreateFoo(args...)
{
FOO *new = malloc(sizeof *new);
if(new != NULL)
{
...set up valid FOO instance...
}
return new;
}
--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton
sugaray wrote: Hi, can somebody help me out with a better version of the following functions which only convert decimal integer to it's corresponding binary form. the problem i'm having now is that I can't figure out how to handle when 0 is passed as parameter in only one function, my code below have to add one more function to handle this situation, any help is appreciated, thanx.
char *Dec2Bin(const int decimal) {
/* BEGIN bitstr.c */
#include <stdio.h>
#include <limits.h>
#define E_TYPE float
#define STRING " %s = %f\n"
typedef E_TYPE e_type;
char *bitstr(char *, void const *, size_t);
int main(void)
{
e_type e, d;
char ebits[CHAR_BIT * sizeof e + 1], *s;
s = STRING;
for (e = 0.2f; 0.75 > e; e += 0.125) {
bitstr(ebits, &e, sizeof e);
printf(s, ebits, e);
}
for (d = 2; 20000 > d; d *= 2) {
for (e = d - 1; 0.75 > e - d; e += 0.5) {
bitstr(ebits, &e, sizeof e);
printf(s, ebits, e);
}
}
return 0;
}
char *bitstr(char *str, const void *obj, size_t n)
{
unsigned char mask;
const unsigned char *byte = obj;
char *const ptr = str;
while (n-- != 0) {
mask = ((unsigned char)-1 >> 1) + 1;
do {
*str++ = (char)(mask & byte[n] ? '1' : '0');
mask >>= 1;
} while (mask != 0);
}
*str = '\0';
return ptr;
}
/* END bitstr.c */
--
pete
> Emmanuel Delahaye wrote: In 'comp.lang.c', ru****@sohu.com (sugaray) wrote:
char *binary=new char[64];
There is no 'new' in C.
It's a perfectly valid identifier name (albeit used in a rather strange and syntactically erroneous manner in the code you quote here). In fact, I often use it myself in code such as:
FOO *prefix_CreateFoo(args...) { FOO *new = malloc(sizeof *new); if(new != NULL) { ...set up valid FOO instance... } return new; }
You can use:
Char* binary = (char*)malloc(sozeof(char)*64); // allocate 64 times space
for a char
assert(binary); // make sure everything went ok (Memoryoverflow asf.)
// donąt forget when you donąt use binary anymore
free(binary);
Georg Troxler wrote: You can use:
Char
Undefined type.
* binary = (char*)
Unnecessary cast.
malloc(sozeof(char)
Undeclared macro, sozeof
*64); // allocate 64 times space
If that's what you want to do, use:
char *binary = malloc(64);
or, perhaps:
char *binary = malloc(64 * sizeof *binary);
for a char
Illegal syntax for for-loop. (Hint: if you must use BCPL/C99 comments, make
sure your lines don't wrap!)
assert(binary); // make sure everything went ok (Memoryoverflow asf.)
This is a lousy use of assert. Assertions are best used for asserting
conditions that /must/ be true if and only if the programmer didn't screw
up. Furthermore, assert(pointerexpression) is not portable to C90.
Far better to check for NULL and handle the out-of-memory condition
robustly.
--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton
Georg Troxler wrote: Char* binary = (char*)malloc(sozeof(char)*64); // allocate 64 times space for a char
#include <stdlb.h>
somewhere
char* binary=malloc(sizeof(char)*64);
or:
char* binary=malloc(64);
assert(binary); // make sure everything went ok (Memoryoverflow asf.)
I don't think this is a good idea.
Imagine the following code:
#define NDEBUG
#include <assert.h>
#include <stdlib.h>
int main(void)
{
char *c;
c=malloc(64);
assert(c);
strcpy(p,"hello");
return 0;
}
In this code strcpy is also executed if c==NULL.
So I do think it is better to use:
if (!c) { /* or if (c==NULL) whatever you prefer */
/*some error handling here*/
}
or
if (c) { /* or if (c!=NULL) */
/*do something with c*/
}
-rb
-- Ro*************@rbdev.net
Robert Bachmann wrote: if (c) { /* or if (c!=NULL) */ /*do something with c*/
I meant: /* do something with *c */ }
-- Ro*************@rbdev.net
Georg Troxler wrote: You can use:
Char* binary = (char*)malloc(sozeof(char)*64); // allocate 64 times space for a char assert(binary); // make sure everything went ok (Memoryoverflow asf.)
What the hell language is this? You _may_ mean
char *binary = malloc(64); /* note the case of 'char', the absence of the
superfluous cast, the absence of the
tautological and misspelled 'sozeof(char) *'
*/
if (!binary) { /* handle error */ }
--
Martin Ambuhl
In article <Xn***************************@213.228.0.75>, em**********@noos.fr
says... In 'comp.lang.c', Richard Heathfield <in*****@address.co.uk.invalid> wrote:
There is no 'new' in C.
It's a perfectly valid identifier name (albeit used in a rather strange and syntactically erroneous manner in the code you quote here). In fact, I often use it myself in code such as:
FOO *prefix_CreateFoo(args...) { FOO *new = malloc(sizeof *new); if(new != NULL) { ...set up valid FOO instance... } return new; }
I prefer to use 'this', in this case!
I suppose this is a good way to make sure you code isn't accidentally
used with a C++ compiler?
--
Randy Howard
2reply remove FOOBAR
Randy Howard wrote: > FOO *prefix_CreateFoo(args...) > { > FOO *new = malloc(sizeof *new); > if(new != NULL) > { > ...set up valid FOO instance... > } > return new; > }
I prefer to use 'this', in this case!
I suppose this is a good way to make sure you code isn't accidentally used with a C++ compiler?
Yes, precisely. C and C++ are divided by a common syntax. It's important not
to mix them up accidentally.
--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton
Emmanuel Delahaye wrote: In 'comp.lang.c', Randy Howard <ra**********@FOOmegapathdslBAR.net> wrote:
I prefer to use 'this', in this case!
I suppose this is a good way to make sure you code isn't accidentally used with a C++ compiler?
He he! I'm not supposed to know a word about C++. But for what you have suggested, I put this on my sources (.c only)
#ifdef __cplusplus #error This source file is not C++ but rather C. Please use a C-compiler #endif
That's fine for C99, but IIRC there is no restriction on C90 compilers
defining __cplusplus for whatever dastardly purpose they choose. Therefore,
tempting as your suggestion is, I cannot adopt it myself.
Of course, I could do this:
static int new;
at the top of every C file. :-)
--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton
In article <40******@news2.power.net.uk>, in*****@address.co.uk.invalid says... Emmanuel Delahaye wrote:
In 'comp.lang.c', Randy Howard <ra**********@FOOmegapathdslBAR.net> wrote:
I prefer to use 'this', in this case!
I suppose this is a good way to make sure you code isn't accidentally used with a C++ compiler? He he! I'm not supposed to know a word about C++. But for what you have suggested, I put this on my sources (.c only)
#ifdef __cplusplus #error This source file is not C++ but rather C. Please use a C-compiler #endif
That's fine for C99, but IIRC there is no restriction on C90 compilers defining __cplusplus for whatever dastardly purpose they choose. Therefore, tempting as your suggestion is, I cannot adopt it myself.
Now, that is pedantic. :-)
Of course, I could do this:
static int new;
at the top of every C file. :-)
Well, you could at least do this...
static int new; /* Hey! this file is NOT valid C++, don't even try. */
and then way down at the bottom somewhere....
static int this; /* Hello! I warned you, do you never give up? */
--
Randy Howard
2reply remove FOOBAR
Richard Heathfield wrote:
.... snip ... Of course, I could do this:
static int new;
at the top of every C file. :-)
Maybe:
static char this, class, new; /* why waste space */
--
Chuck F (cb********@yahoo.com) (cb********@worldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home.att.net> USE worldnet address!
Randy Howard wrote: In article <40******@news2.power.net.uk>, in*****@address.co.uk.invalid says... Emmanuel Delahaye wrote:
> #ifdef __cplusplus > #error This source file is not C++ but rather C. Please use a > #C-compiler endif
That's fine for C99, but IIRC there is no restriction on C90 compilers defining __cplusplus for whatever dastardly purpose they choose. Therefore, tempting as your suggestion is, I cannot adopt it myself.
Now, that is pedantic. :-)
Of course. If we're going to discuss C, we might as well discuss it
properly.
--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton
"sugaray" <ru****@sohu.com> wrote in message
news:ad**************************@posting.google.c om... Hi, can somebody help me out with a better version of the following functions which only convert decimal integer to it's corresponding binary form. the problem i'm having now is that I can't figure out how to handle when 0 is passed as parameter in only one function, my code below have to add one more function to handle this situation, any help is appreciated, thanx.
char *Dec2Bin(const int decimal) {
char *binary=new char[64]; int dividend,i;
dividend=decimal; for(i=0;dividend!=0;++i) { binary[i]=(dividend&1)+'0'; // (a % b) == (a & (b-1)) dividend>>=1; } binary[i]='\0';
return strrev(binary); }
char *Decimal2Binary(const int decimal) { return (decimal==0)?"0":Dec2Bin(decimal); }
Why not fill the string from the left, thus avoiding the need to do strrev ?
Something like this?
char *Dec2Bin(const unsigned int decimal) {
int i,num_bits;
char *binary;
num_bits=sizeof(int)*8;
binary=calloc(1,num_bits+1);
for(i=num_bits;i>=0;i--)
binary[num_bits-i]=((1<<i)&decimal)+'0';
return binary;
}
If you don't want the trailing '0's then add a flag which gets set when the
first non zero bit is reached and check against this flag inside your inner
loop so that all future '0's get written.
Note I have also changed the function argument to unsigned int since I think
there might be some implementation issues with using signed integers..
Sean
"Sean Kenwrick" <sk*******@hotmail.com> wrote in message
news:bv**********@sparta.btinternet.com... "sugaray" <ru****@sohu.com> wrote in message news:ad**************************@posting.google.c om... Hi, can somebody help me out with a better version of the following functions which only convert decimal integer to it's corresponding binary form. the problem i'm having now is that I can't figure out how to handle when 0 is passed as parameter in only one function, my code below have to add one more function to handle this situation, any help is appreciated, thanx.
char *Dec2Bin(const int decimal) {
char *binary=new char[64]; int dividend,i;
dividend=decimal; for(i=0;dividend!=0;++i) { binary[i]=(dividend&1)+'0'; // (a % b) == (a & (b-1)) dividend>>=1; } binary[i]='\0';
return strrev(binary); }
char *Decimal2Binary(const int decimal) { return (decimal==0)?"0":Dec2Bin(decimal); } Why not fill the string from the left, thus avoiding the need to do strrev
? Something like this?
char *Dec2Bin(const unsigned int decimal) { int i,num_bits; char *binary;
num_bits=sizeof(int)*8; binary=calloc(1,num_bits+1);
for(i=num_bits;i>=0;i--) binary[num_bits-i]=((1<<i)&decimal)+'0';
return binary; }
If you don't want the trailing '0's then add a flag which gets set when
the first non zero bit is reached and check against this flag inside your
inner loop so that all future '0's get written.
Note I have also changed the function argument to unsigned int since I
think there might be some implementation issues with using signed integers..
Sean
There is an error in the above it should read something like:
binary[num_bits-i]=((1<<i)&decimal)?'1':'0';
Sean
"Richard Heathfield" <in*****@address.co.uk.invalid> wrote in message
news:40******@news2.power.net.uk... Randy Howard wrote:
In article <40******@news2.power.net.uk>, in*****@address.co.uk.invalid says... Emmanuel Delahaye wrote:
> #ifdef __cplusplus > #error This source file is not C++ but rather C. Please use a > #C-compiler endif
That's fine for C99, but IIRC there is no restriction on C90 compilers defining __cplusplus for whatever dastardly purpose they choose. Therefore, tempting as your suggestion is, I cannot adopt it myself.
Now, that is pedantic. :-)
Of course. If we're going to discuss C, we might as well discuss it properly.
N847 seems to say there _was_ an agreed proposal for C90 (re not defining
__cplusplus) which got "lost".
Personally, that's near enough for me. We all make the occasional clerical
errors. That shouldn't distract us... ;-)
--
Peter This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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