Playing with different scenarios with Objective-C's BOOL type

bool.m

#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