C
cai_rongxi
I know how to write c code to realize atoi function, but I don't know
how to do the opposit. Any sample code is appreciated.
how to do the opposit. Any sample code is appreciated.
L
Lew Pitcher
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You can check the archives of this newsgroup for a number of solutions. One
that I contributed long ago can be found at
http://groups.google.com/groups?hl=en&lr=&[email protected]
- --
Lew Pitcher
Master Codewright & JOAT-in-training | GPG public key available on request
Registered Linux User #112576 (http://counter.li.org/)
Slackware - Because I know what I'm doing.
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=NELE
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Hash: SHA1
You can check the archives of this newsgroup for a number of solutions. One
that I contributed long ago can be found at
http://groups.google.com/groups?hl=en&lr=&[email protected]
- --
Lew Pitcher
Master Codewright & JOAT-in-training | GPG public key available on request
Registered Linux User #112576 (http://counter.li.org/)
Slackware - Because I know what I'm doing.
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Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org
iD8DBQFBpAdKagVFX4UWr64RAq9bAKCpABdkOOhh3OCtXE54OLunXCwCOgCg5Fcw
+CFp4sh/zmzAhCR6c1hbw0k=
=NELE
-----END PGP SIGNATURE-----
E
Erik de Castro Lopo
Without any error checking:
char * itoa (int i)
{
char str_val [32] ;
snprintf (str_val, sizeof (str_val), "%d", i) ;
/* Use strdup to duplicate str_val which is currently on the stack. */
return strdup (str_val) ;
}
--
+-----------------------------------------------------------+
Erik de Castro Lopo (e-mail address removed) (Yes it's valid)
+-----------------------------------------------------------+
`[Microsoft] are in the business of giving customers exactly what they ask
for, which sounds like a nice idea until you realize that most Microsoft
customers are idiots.' --- Eugene O'Neil on comp.os.linux.development.system
J
jt
/* atoi example */
#include <stdio.h>
#include <stdlib.h>
int main ()
{
int i;
char szInput [256];
printf ("Enter a number: ");
gets ( szInput );
i = atoi (szInput);
printf ("Value entered is %d, and its double %d",i,i*2);
return 0;
}
Output:
Enter a number: 73
Value entered is 73, and its double 146
C
Chris Barts
jt said:
If your compiler or linker doesn't throw up a warning about this line,
your tools are broken and need to be replaced for the good of everyone
who uses code you compile.
Besides, your code doesn't help him do anything about writing an itoa
function.
S
suman kar
A quick and dirty hack would be using sprintf() function, which you can
find in stdio.h, a standard library.Don't ask for code for this one
Regards,
Suman.
S
Souvik
Here's one:
#include "stdio.h"
#include "string.h"
void itochar(int x, char *szBuffer, int radix);
int main()
{
char szBuffer[10];
itochar(725, szBuffer, 10);
printf ("%s", szBuffer);
return 0;
}
void itochar(int x, char *szBuffer, int radix)
{
int i = 0 , n,xx;
n = x;
while (n > 0)
{
xx = n%radix;
n = n/radix;
szBuffer[i++] = '0' + xx;
}
szBuffer = '\0';
strrev(szBuffer);
}
M
Michael Mair
What will you do for base 2? Or log(INT_MAX)/log(10)>10?Souvik said:
It is a Good Idea to pass the buffer size, too.
A newline character is required if you want to have that output;
printf ("%s", szBuffer);
Nice, but will not work for radices > 10. Use a string
with your symbols instead, e.g.
szBuffer[i++] = "0123456789abcdefghijklmnopqrstuvwxyz"[xx];
Apart from that, your code does not work with negative numbers.
They must have left that one out of my standard; at least
there is nothing between strrchr() and strspn()...
Functions of your own should not start with str in order to
not clash with future library extensions.
BTW: itochar could be written in a more compact way without use of
i,n,xx.
Cheers
Michael
R
Randy Howard
You should just plonk yourself for posting code using gets.
M
Malcolm
Take modulus ten, convert to a digit. The divide by ten. Take modulus ten to
get the next digit, and so on until your number reaches zero. Then reverse
the digits.
You can easily extend to negative numbers by adding a minus sign and
negating, unless you are passed INT_MIN. This probably won't matter.
P
pete
#include <limits.h>
void itoa_1(int n, char *s)
{
int tenth, min_flag;
char swap, *p;
min_flag = 0;
if (0 > n) {
*s++ = '-';
n = -INT_MAX > n ? min_flag = INT_MAX : -n;
}
p = s;
do {
tenth = n / 10;
*p++ = (char)(n - 10 * tenth + '0');
n = tenth;
} while (n != 0);
if (min_flag != 0) {
++*s;
}
*p-- = '\0';
while (p > s) {
swap = *s;
*s++ = *p;
*p-- = swap;
}
}
static char *sput_u(unsigned n, char *s);
static char *sput_up1(unsigned n, char *s);
void itoa_2(int n, char *s)
{
if (0 > n) {
*s++ = '-';
*sput_up1(-(n + 1), s) = '\0';
} else {
*sput_u(n, s) = '\0';
}
}
static char *sput_u(unsigned n, char *s)
{
unsigned tenth;
tenth = n / 10;
if (tenth != 0) {
s = sput_u(tenth, s);
}
*s = (char)(n - 10 * tenth + '0');
return s + 1;
}
static char *sput_up1(unsigned n, char *s)
{
unsigned digit, tenth;
tenth = n / 10;
digit = n - 10 * tenth;
if (digit == 9) {
if (tenth != 0) {
s = sput_up1(tenth, s);
} else {
*s++ = '1';
}
*s = '0';
} else {
if (tenth != 0) {
s = sput_u(tenth, s);
}
*s = (char)('1' + digit);
}
return s + 1;
}