Last active
August 29, 2015 14:27
-
-
Save piguet-b/271f856cdd8d45bd6105 to your computer and use it in GitHub Desktop.
Example of a definition and use of a lenient version of ut_compare
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
/** | |
* Demonstration of the strict behaviour of ut_compare(), (for some values | |
* of unit, ut_compare(unit, (ut_parse(ut_format(unit))) != 0), and | |
* of a more lenient version. | |
* | |
* compile with : | |
* gcc -O pb_compare.c -ludunits2 -o pb_compare | |
*/ | |
#include <stdio.h> | |
#include <string.h> | |
#include <stdlib.h> | |
#include <math.h> | |
#include <udunits2/udunits2.h> | |
static ut_system *unitSystem; | |
int | |
my_ut_compare_pragmatic (const ut_unit * unit1, const ut_unit * unit2) | |
{ | |
int CodRet; | |
ut_unit *ratio_ut_unit; | |
double ratio_double; | |
char buf[120]; | |
char *endptr; | |
CodRet = ut_compare (unit1, unit2); | |
if (CodRet == 0) | |
return CodRet; | |
/* "This function returns a non-zero value if conversion is possible; | |
* otherwise, 0 is returned" */ | |
CodRet = ut_are_convertible (unit1, unit2); | |
/* if conversion impossible, exit */ | |
if (CodRet == 0) | |
return -5; | |
/* let's see if conversion ratio is close to 1 */ | |
ratio_ut_unit = ut_divide (unit1, unit2); | |
if (ratio_ut_unit == NULL) | |
return -6; | |
/* Don't know how to get the value from an ut_unit variable. | |
* So, let's format it and parse the resulting string */ | |
CodRet = ut_format (ratio_ut_unit, buf, sizeof (buf), UT_ASCII); | |
ut_free (ratio_ut_unit); | |
ratio_ut_unit = NULL; | |
if ((CodRet < 0) || (CodRet >= (int) sizeof (buf))) | |
{ | |
return -7; | |
} | |
/* the end must be " 1" (meaning dimensionless) */ | |
if ((strlen (buf) > 2) && (!strcmp (buf + strlen (buf) - 2, " 1"))) | |
{ | |
buf[strlen (buf) - 2] = 0; | |
ratio_double = strtod (buf, &endptr); | |
if ((*endptr == 0) && (fabs (1.0 - ratio_double) < 1.0e-8)) | |
{ | |
/* Approximately equal --> OK ! */ | |
return 0; | |
} | |
} | |
return -8; | |
} | |
void | |
test_back_forth (const char *unit_str) | |
{ | |
ut_unit *unit_1, *unit_2; | |
char buf[120]; | |
int len, cmp_cod; | |
unit_1 = ut_parse (unitSystem, unit_str, UT_ASCII); | |
if (unit_1 == NULL) | |
{ | |
fprintf (stderr, "Error %d parsing : %s\n", ut_get_status (), unit_str); | |
return; | |
} | |
len = ut_format (unit_1, buf, sizeof (buf), UT_ASCII); | |
if ((len < 0) || (len >= (int) sizeof (buf))) | |
{ | |
fprintf (stderr, "Error %d writing unit\n", ut_get_status ()); | |
ut_free (unit_1); | |
return; | |
} | |
fprintf (stdout, "%s formatted as : %s\n", unit_str, buf); | |
unit_2 = ut_parse (unitSystem, buf, UT_ASCII); | |
if (unit_2 == NULL) | |
{ | |
fprintf (stderr, "Error %d parsing : %s\n", ut_get_status (), buf); | |
ut_free (unit_1); | |
return; | |
} | |
cmp_cod = ut_compare (unit_1, unit_2); | |
fprintf (stdout, " ut_compare(%s, %s) = %d\n", unit_str, buf, cmp_cod); | |
cmp_cod = my_ut_compare_pragmatic (unit_1, unit_2); | |
fprintf (stdout, " my_ut_compare(%s, %s) = %d\n", unit_str, buf, | |
cmp_cod); | |
ut_free (unit_1); | |
ut_free (unit_2); | |
} | |
int | |
main (int argc, char *argv[]) | |
{ | |
const char *unit_tab[] = { "degree", | |
"kt", | |
"ft/min", | |
"mm/h", | |
"l/min" | |
}; | |
unsigned long nb_unit = sizeof (unit_str) / sizeof (*unit_str); | |
unsigned long i; | |
unitSystem = ut_read_xml (NULL); | |
if (unitSystem == NULL) | |
return 1; | |
for (i = 0; i < nb_unit; i++) | |
test_back_forth (unit_tab[i]); | |
ut_free_system (unitSystem); | |
return 0; | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment