C/Macro Preprocessor/if def
Содержание
#define and #ifdef
//file1.h
#define USD 1
//file2.h
#define UKP 1
//file3
#include <stdio.h>
#include <file1.h>
#if !defined (USD) || !defined (UKP)
#error "RROR: NO_CURRENCY rate is specified."
#endif
main() {
int rs;
rs = 10 * currency_rate;
printf ("d\n", rs);
}
#define, #ifdef #else example
#include <stdio.h>
#define TED 10
int main(void)
{
#ifdef TED
printf("Hi Ted\n");
#else
printf("Hi anyone\n");
#endif
#ifndef RALPH
printf("RALPH not defined\n");
#endif
return 0;
}
Simple #if/#else example
#include <stdio.h>
#define MAX 10
int main(void)
{
#if MAX>99
printf("Compiled for array greater than 99.\n");
#else
printf("Compiled for small array.\n");
#endif
return 0;
}
Simple #if example
#include <stdio.h>
#define MAX 100
int main(void)
{
#if MAX>99
printf("Compiled for array greater than 99.\n");
#endif
return 0;
}