C Tutorial/Preprocessor/if

#if

To define more generalized conditions.

Multiple conditions are connected by relational operators such as AND(&&), OR(||).

<source lang="cpp">#define USA 1 // #define EUP 1

1. include <stdio.h>
2. if ((1>0) && defined USA)

      #define currency_rate 46

1. endif
2. if (defined (EUP))

  #define currency_rate 100

1. endif

main() {

   int rs;
   rs = 10 * currency_rate;
   printf ("%d\n", rs);

}</source>

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