char -> int

[ern]

Anybody know a quick and dirty function for going from "547.645867 9" to
the integer version 548 ?

i.e.

int returnIntegerEq uivalent(char * charNum){
int intNum;
//Do some stuff...
return intNum;
}

I was using the Windows stuff before (ie _gcvt() and atof()).
Thanks,

[John Bode]

ern wrote:

Anybody know a quick and dirty function for going from "547.645867 9" to
the integer version 548 ?

i.e.

#include <stdlib.h>
#include <math.h>
int returnIntegerEq uivalent(char * charNum){
int intNum;
double dNum = strtod(charNum, NULL);
if (ceil(dNum) - dNum > 0.5)
intNum = (int) floor(dNum);
else
intNum = (int) ceil(dNum);
return intNum;
}

I was using the Windows stuff before (ie _gcvt() and atof()).
Thanks,

[tedu]

ern wrote:

Anybody know a quick and dirty function for going from "547.645867 9" to
the integer version 548 ?

i.e.

int returnIntegerEq uivalent(char * charNum){
int intNum;
//Do some stuff...
intNum = atof(charNum) + 0.5;
return intNum;
}

I was using the Windows stuff before (ie _gcvt() and atof()).
Thanks,

[Alexei A. Frounze]

"ern" <er*******@gmai l.com> wrote in message
news:11******** *************@g 14g2000cwa.goog legroups.com...

Anybody know a quick and dirty function for going from "547.645867 9" to
the integer version 548 ?

rounding to +infinity is done with ceil()
examples:
547.6 -> 548
547.4 -> 548
547 -> 547
-547.4 -> -547
-547.6 -> -547

rounding to -infinity is done with floor()
examples:
547.6 -> 547
547.4 -> 547
547 -> 547
-547.4 -> -548
-547.6 -> -548

truncating the fractional part is done by converting/casting to integer
type:
547.6 -> 547
547.4 -> 547
547 -> 547
-547.4 -> -547
-547.6 -> -547

rounding to the nearest integer can be achieved from truncating if 0.5 is
first [added to]/[subtracted from] the number being rounded:
547.6+0.5 -> 548
547.4+0.5 -> 547
547+0.5 -> 547
-547.4-0.5 -> -547
-547.6-0.5 -> -548

Something like that,
Alex

[Charles M. Reinke]

"ern" <er*******@gmai l.com> wrote in message
news:11******** *************@g 14g2000cwa.goog legroups.com...

Anybody know a quick and dirty function for going from "547.645867 9" to
the integer version 548 ?

i.e.

int returnIntegerEq uivalent(char * charNum){
int intNum;
//Do some stuff...
return intNum;
}

I was using the Windows stuff before (ie _gcvt() and atof()).
Thanks,

I'm not sure how "dirty" (or quick, for that matter) it is, but you'll
probably want to look into the strtol() function:
http://ccs.ucsd.edu/c/stdlib.html#strtol. More intuitively, you could
convert the string to a (double) using the related strtod() function
(http://ccs.ucsd.edu/c/stdlib.html#strtod), and then cast the result to an
(int), especially since you have to do that anyway with strtol() unless you
declare "intNUM" of type (long).

-Charles

[Martin Ambuhl]

ern wrote:

Anybody know a quick and dirty function for going from "547.645867 9" to
the integer version 548 ?

i.e.

int returnIntegerEq uivalent(char * charNum){
int intNum;
//Do some stuff...
return intNum;
}

I was using the Windows stuff before (ie _gcvt() and atof()).
Thanks,

#include <errno.h>
#include <stdlib.h>
#include <math.h>
#include <stdio.h>

/* making no assumption that s represents an value in the range of an
int, but accepting that some initial portion is supposed to represent
a legal double value. 0 is returned (with errno set) if a problem occurs
with the string to float conversion. */

double floatingstring2 floatingint(con st char *s)
{
double x, fp, ip;
int sign = 1;
errno = 0;
x = strtod(s, 0);
if (errno)
return 0;
if (x < 0) {
sign = -1;
x = -x;
}
fp = modf(x, &ip);
if (fp >= .5)
ip++;
return sign * ip;
}

int main(void)
{
char s[] = "547.645867 9";
char t[] = "-547.6458679";
printf("The initial string (s) is \"%s\n", s);
printf("floatin gstring2floatin gint(s) returns %g\n",
floatingstring2 floatingint(s)) ;
printf("The initial string (t) is \"%s\n", t);
printf("floatin gstring2floatin gint(t) returns %g\n",
floatingstring2 floatingint(t)) ;
return 0;
}

The initial string (s) is "547.645867 9
floatingstring2 floatingint(s) returns 548
The initial string (t) is "-547.6458679
floatingstring2 floatingint(t) returns -548

[Charles M. Reinke]

"Charles M. Reinke" <cm******@ece.g atech.edu> wrote in message
news:dh******** **@news-int.gatech.edu. ..

"ern" <er*******@gmai l.com> wrote in message
news:11******** *************@g 14g2000cwa.goog legroups.com...

Anybody know a quick and dirty function for going from "547.645867 9" to
the integer version 548 ?

i.e.

int returnIntegerEq uivalent(char * charNum){
int intNum;
//Do some stuff...
return intNum;
}

I was using the Windows stuff before (ie _gcvt() and atof()).
Thanks,

I'm not sure how "dirty" (or quick, for that matter) it is, but you'll
probably want to look into the strtol() function:
http://ccs.ucsd.edu/c/stdlib.html#strtol. More intuitively, you could
convert the string to a (double) using the related strtod() function
(http://ccs.ucsd.edu/c/stdlib.html#strtod), and then cast the result to an
(int), especially since you have to do that anyway with strtol() unless

you declare "intNUM" of type (long).

-Charles

After sending my inital response I realized that the proper solution could
be a little complicated, hence the following code:
holomask>cat h.c
#include <stdlib.h>
#include <stdio.h>
#include <math.h>

int returnIntegerEq uivalent(char *charNum) {
int intNum;
char *str_test;

intNum = floor(strtod(ch arNum, &str_test)+0.5) ;
if(charNum==str _test)
printf("Error converting string.\n");

return intNum;
} /* returnIntegerEq uivalent */

int main(void) {
int intNum;
char charNum[]="547.645867 9";

intNum = returnIntegerEq uivalent(charNu m);
printf("test string: %s\ninteger value: %d\n", charNum, intNum);

return 0;
} /* main */
holomask>gcc -Wall -ansi -pedantic -lm -o h.exe h.c
holomask>h.exe
test string: 547.6458679
integer value: 548

[A. Sinan Unur]

"Charles M. Reinke" <cm******@ece.g atech.edu> wrote in
news:dh******** **@news-int.gatech.edu:

intNum = floor(strtod(ch arNum, &str_test)+0.5) ;
if(charNum==str _test)
printf("Error converting string.\n");

In cases like this, it might be more useful to test that the string
contained nothing other than a valid number. For example, the test above
would not raise an error if

"547.64.586 79"

was passed to it.

Thus, a test like

if( *str_test ) {
/* error */
}

might be more useful in practice.

Sinan
--
A. Sinan Unur <1u**@llenroc.u de.invalid>
(reverse each component and remove .invalid for email address)

[Charles M. Reinke]

"A. Sinan Unur" <1u**@llenroc.u de.invalid> wrote in message
news:Xn******** *************** *****@127.0.0.1 ...

In cases like this, it might be more useful to test that the string
contained nothing other than a valid number. For example, the test above
would not raise an error if

"547.64.586 79"

was passed to it.
Agreed.
Thus, a test like

if( *str_test ) {
/* error */
}

might be more useful in practice.

Sinan

Point well taken. ;-)

-Charles

[A. Sinan Unur]

"Charles M. Reinke" <cm******@ece.g atech.edu> wrote in
news:dh******** **@news-int.gatech.edu:

"A. Sinan Unur" <1u**@llenroc.u de.invalid> wrote in message
news:Xn******** *************** *****@127.0.0.1 ...

In cases like this, it might be more useful to test that the string
contained nothing other than a valid number. For example, the test
above would not raise an error if

"547.64.586 79"

was passed to it.
Agreed.

Thus, a test like

if( *str_test ) {
/* error */
}

might be more useful in practice.

....

Point well taken. ;-)

I should note that this requires str_test to be initialized.

char *str_test = charNum;

should be good enough.

--
A. Sinan Unur <1u**@llenroc.u de.invalid>
(reverse each component and remove .invalid for email address)

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