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// C preprocessor - conditional inclusion
// Source: https://en.cppreference.com/w/c/preprocessor/conditional
#define ABCD 2
#include <stdio.h>
int main(void)
{
#ifdef ABCD
printf("1: yes\n");
#else
printf("1: no\n");
#endif
#ifndef ABCD
printf("2: no1\n");
#elif ABCD == 2
printf("2: yes\n");
#else
printf("2: no2\n");
#endif
#if !defined(DCBA) && (ABCD < 2 * 4 - 3)
printf("3: yes\n");
#endif
// C23 directives #elifdef/#elifndef
#ifdef CPU
printf("4: no1\n");
#elifdef GPU
printf("4: no2\n");
#elifndef RAM
printf("4: yes\n"); // selected in C23 mode, may be selected in pre-C23 mode
#else
printf("4: no3\n"); // may be selected in pre-C23 mode
#endif
}
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