Null Value (.NULL.) Is a Marker - Not a Data Type

MORE INFORMATION

Steps to Demonstration Behavior

1. From the Command window, issue these commands:

      nMyvariable=200        && and press ENTER
      ? TYPE("nMyvariable")  && and press ENTER
      ? nMyvariable
   						

   The N is displayed for nMyvariable denoting a variable of numeric type.
2. To assign a null value (.NULL.) to nMyvariable, issue the following commands in the Command window:

      store .NULL. to nMyvariable        && and press ENTER
      ? TYPE("nMyvariable")              && and press ENTER
      ? nMyvariable                      && and press ENTER
   						

   The value N is displayed followed by .NULL.; the type of the variable did not change but the value did.
3. To assign a character string to the variable and check the variable type, issue the following commands in the Command window:

      cMyvariable="This is a String"     && and press ENTER
      ? cMyvariable                      && and press ENTER
   						

   The screen displays the string "This is a String."
4. Issue the following command in the Command window:

      ? TYPE("cMyvariable")              && and press ENTER
   						

   The screen displays C denoting a character type.
5. Issue the following commands in the Command window:

      STORE .NULL. TO cMyvariable        && and press ENTER
      ?TYPE("cMyvariable")               && and press ENTER
   						

   The screen displays C to show that the type has not been changed.