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http://f.osdev.org/
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|63..32|31..16|15-8|7-0|
|AX.....|
|EAX............|
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Why would you need to? Can you possibly give us a little more information about what you're trying to achieve?how can we tell the OS is 64bit or 32bit
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int main() {
switch (sizeof(void*)) {
case 1: printf("8 bit\n"); break;
case 2: printf("16 bit\n"); break;
case 4: printf("32 bit\n"); break;
case 8: printf("64 bit\n"); break;
default: printf("uh...\n");
}
return 0;
}
Or evenNickJohnson wrote:If you are talking about your host operating system (or at least your host compiler, which is what matters), this will tell you:
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int main() { switch (sizeof(void*)) { case 1: printf("8 bit\n"); break; case 2: printf("16 bit\n"); break; case 4: printf("32 bit\n"); break; case 8: printf("64 bit\n"); break; default: printf("uh...\n"); } return 0; }
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int main(void) {
printf("%d bit\n", sizeof(void *) * 8);
return 0;
}
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#include <limits.h>
#include <stdio.h>
int main(void)
{
printf("%d bits", sizeof(void*) * CHAR_BIT);
return 0;
}