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Playing with different scenarios with Objective-C's BOOL type
#import <Foundation/Foundation.h>
// clang -g -Wall -framework Foundation -o bool bool.m
// Are these two integers different? YES if so, NO if not
// (even though it says YES and NO, it LIES! Can actualy return a range
// of non-YES values)
static BOOL different (int thing1, int thing2) {
return thing1 - thing2;
} // difference
// Are these two integers different? true if so, false if not
// Thiso one is actually reliable.
static bool std_different (int thing1, int thing2) {
return thing1 - thing2;
} // difference
static BOOL same (int thing1, int thing2) {
return !(thing1 - thing2); // logical expression always 0 or 1
} // difference
static NSString *g_name;
static BOOL haveName () {
return (BOOL)g_name;
} // haveName
static bool stdHaveName () {
return (bool)g_name;
} // stdHaveName
int main (void) {
printf ("Slice\n");
BOOL truefalse;
truefalse = (BOOL)256;
printf ("256 -> %d (BOOL)\n", truefalse);
bool stdTruefalse;
stdTruefalse = (bool)256;
printf ("256 -> %d (bool)\n", stdTruefalse);
printf ("\nDifference\n");
if (different(11, 10) == YES) printf ("11 != 10\n");
else printf ("11 == 10\n");
if (different(10, 11) == YES) printf ("10 != 11\n");
else printf ("10 == 11\n");
if (different(10, 15) == YES) printf ("10 != 15\n");
else printf ("10 == 15\n");
if (different(512, 256) == YES) printf ("512 != 256\n");
else printf ("512 == 256\n");
printf ("%d %d %d %d\n",
different(11, 10), different(10, 11),
different(10, 15), different(512, 256));
printf ("\nStd Difference\n");
if (std_different(10, 11) == YES) printf ("10 != 11\n");
else printf ("10 == 11\n");
if (std_different(11, 10) == YES) printf ("11 != 10\n");
else printf ("11 == 10\n");
if (std_different(10, 15) == YES) printf ("10 != 15\n");
else printf ("10 == 15\n");
if (std_different(512, 256) == YES) printf ("512 != 256\n");
else printf ("512 == 256\n");
printf ("\nSame Difference\n");
if (same(10, 11) == YES) printf ("10 == 11\n");
else printf ("10 != 11\n");
if (same(11, 10) == YES) printf ("11 == 10\n");
else printf ("11 != 10\n");
if (same(512, 256) == YES) printf ("512 == 256\n");
else printf ("512 != 256\n");
printf ("\nAddress (BOOL)\n");
g_name = nil;
if (haveName()) printf ("%p means name set\n", g_name);
else printf ("%p means name not set\n", g_name);
g_name = (NSString *)0x12345678;
if (haveName()) printf ("%p means name set\n", g_name);
else printf ("%p means name not set\n", g_name);
g_name = (NSString *)0x12345600;
if (haveName()) printf ("%p means name set\n", g_name);
else printf ("%p means name not set\n", g_name);
printf ("\nAddress (std)\n");
g_name = nil;
if (stdHaveName()) printf ("%p means name set\n", g_name);
else printf ("%p means name not set\n", g_name);
g_name = (NSString *)0x12345678;
if (stdHaveName()) printf ("%p means name set\n", g_name);
else printf ("%p means name not set\n", g_name);
g_name = (NSString *)0x12345600;
if (stdHaveName()) printf ("%p means name set\n", g_name);
else printf ("%p means name not set\n", g_name);
return 0;
} // main
#if SAMPLE_RUN
% ./bool
Slice
256 -> 0 (BOOL)
256 -> 1 (bool)
Difference
open -11 != 10
10 == 11
10 == 15
512 == 256
1 -1 -5 0
Std Difference
10 != 11
11 != 10
10 != 15
512 != 256
Same Difference
10 != 11
11 != 10
512 != 256
Address (BOOL)
0x0 means name not set
0x12345678 means name set
0x12345600 means name not set
Address (std)
0x0 means name not set
0x12345678 means name set
0x12345600 means name set
#endif
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