Sams Teach Yourself C in 21 Days

printf(“*”);

}

}

2. Write a function that verifies that a character is a vowel.


3. Write a function that returns 0 if it receives a character that isn’t a letter of the
   alphabet, 1 if it is an uppercase letter, and 2 if it is a lowercase letter. Keep the
   function as portable as possible.
   4.ON YOUR OWN:Understand your compiler. Determine what flags must be set to
   ignore variable case, allow for byte alignment, and guarantee ANSI compatibility.


4. Is the following code portable?
   void list_a_file( char *file_name )
   {
   system(“TYPE “ file_name );
   }


5. Is the following code portable?
   int to_upper( int x )
   {
   if( x >= ‘a’ && x <= ‘z’ )
   {
   toupper( x );
   }
   return( x );
   }

822 Appendix D

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