Complying with standard C

Third example: integral constants

In the following code, assume ints are 16 bits.

   int f(void)
   {
       int i = 0;
   
       return i > 0xffff;
   }

Because the hexadecimal constant's type is either int (with a value of -1 on a two's-complement machine) or an unsigned int (with a value of 65535), the comparison will be true on a non-ANSI C compiler (-Xt and -Xk modes), and false on an ANSI C compiler (-Xa, -Xc, and -Xm modes).

An appropriate cast clarifies the code and silences the ANSI C compiler:

Non-ANSI C behavior:

   i > (int)0xffff

ANSI C behavior:

   i > (unsigned int)0xffff
          or
   i > 0xffffU

(The U suffix character is a new feature of ANSI C and will probably produce an error message with older compilers.)