How to make itoa write the left zeros?

pajaro · 03-10-2009, 11:39 AM

Hello,
I' trying to convert hexadecimal to binary, I'm using itoa and it seems to be working right, the problem is that it skip every zero at the left of the first one. Is there any way to force it to write this zeros?

Code:

printf("%s ", itoa(str2 , str, 2) );

if str2="f" everything is Ok, it prints 1111
if str2="2" it prints only 10, I would like to print 0010

Thanks in advance

baccardi · 03-10-2009, 11:52 AM

check the strlen() of received string and do the loop:
for (i = 1; i <= 4 - strlen(itoa(...))); i++)
printf("0");

iMalc · 03-10-2009, 12:13 PM

I think that the most efficient option in this case would be to not use itoa. It's not designed for what you want. Just declare a mask variable, make a loop that loops until the mask is zero, shifting it right each time, then test each bit of the input by anding it with the mask.

Code:

char buffer[16], len= 0;
for (int mask = 0x8; mask > 0; mask >>= 1)
{
    buffer[len++] = (input & mask) ? '1' : '0';
}
buffer[len++] = '\0';

vart · 03-10-2009, 12:44 PM

better to make mask unsigned int

CaliJoe · 03-10-2009, 12:46 PM

sorry to both you, but i just joined the fourm and i am wondering how do i start a new post because i have a question with my code? thanks

C_ntua · 03-10-2009, 12:48 PM

Press new thread where the rest questions are. Search and you will see it

03-10-2009, 11:39 AM	#1
pajaro Registered User Join Date: Mar 2009 Posts: 4	How to make itoa write the left zeros? Hello, I' trying to convert hexadecimal to binary, I'm using itoa and it seems to be working right, the problem is that it skip every zero at the left of the first one. Is there any way to force it to write this zeros? Code: printf("%s ", itoa(str2 , str, 2) ); if str2="f" everything is Ok, it prints 1111 if str2="2" it prints only 10, I would like to print 0010 Thanks in advance
pajaro is offline

03-10-2009, 11:52 AM	#2
baccardi Registered User Join Date: Jan 2009 Posts: 26	check the strlen() of received string and do the loop: for (i = 1; i <= 4 - strlen(itoa(...))); i++) printf("0");
baccardi is offline

03-10-2009, 12:13 PM	#3
iMalc Algorithm Dissector Join Date: Dec 2005 Location: New Zealand Posts: 2,476	I think that the most efficient option in this case would be to not use itoa. It's not designed for what you want. Just declare a mask variable, make a loop that loops until the mask is zero, shifting it right each time, then test each bit of the input by anding it with the mask. Code: char buffer[16], len= 0; for (int mask = 0x8; mask > 0; mask >>= 1) { buffer[len++] = (input & mask) ? '1' : '0'; } buffer[len++] = '\0'; __________________ My homepage Advice: Take only as directed - If symptoms persist, please see your debugger
iMalc is offline

03-10-2009, 12:44 PM	#4
vart CSharpener Join Date: Oct 2006 Posts: 5,242	better to make mask unsigned int __________________ If I have eight hours for cutting wood, I spend six sharpening my axe.
vart is offline

03-10-2009, 12:46 PM	#5
CaliJoe Registered User Join Date: Mar 2009 Posts: 16	sorry to both you, but i just joined the fourm and i am wondering how do i start a new post because i have a question with my code? thanks
CaliJoe is offline

03-10-2009, 12:48 PM	#6
C_ntua Registered User Join Date: Jun 2008 Posts: 1,134	Press new thread where the rest questions are. Search and you will see it
C_ntua is offline

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
"Cannot make pipe"	crepincdotcom	C Programming	5	08-16-2004 12:43 PM
Request for comments	Prelude	A Brief History of Cprogramming.com	15	01-02-2004 10:33 AM
Question about atheists	gcn_zelda	A Brief History of Cprogramming.com	160	08-11-2003 11:50 AM
How can we write a C shell script to make Dirs	Unregistered	Linux Programming	3	04-27-2002 10:27 PM
write then make R-O	confusedcoder	C++ Programming	1	01-25-2002 07:53 AM