Variant Records

• C provides a union data type which can be used for variant records.
• They are declared and used in a much same way as structs:

  	union number {
  	    int       int_val;
  	    double    double_val;
  	};
  
  	union number  a_num;
  
  	a_num.int_val = 0;
  	.
  	.
  	if( 9 == a_num.int_val ){
  	    /* do something */
  	}
  

• However, each of the members occupies the same storage.
• Thus, a union can hold only one item at a time.
• It is important to realize that it is the responsibility of the programmer to keep track of which type is currently stored in the union.