CHECK TYPE

Check at runtime the specified type of a variable or function\/procedure parameter

The checking the type of a variable or a function\/procedure parameter is useful for a defensive programming (minimization of input errors)

CHECK TYPE [ SOFT ] <VarName1> AS <VarType1> [ , < VarName2> AS < VarType2> [, < VarNameN> AS < VarTypeN> ] ]

Where:

<VarName> --> is the name of variable
<VarType> --> is one of the following variable types:
- ARRAY
- BLOCK
- CHARACTER
- DATE
- HASH
- LOGICAL
- NIL
- NUMERIC
- MEMO
- POINTER
- SYMBOL
- TIMESTAMP
- OBJECT
- USUAL (the variable can take any of the above types, in the practice the variable type is not checked)

SOFT --> when the SOFT clause is specified the variable can take the NIL value or the specified value, otherwise the variable can take only the value specified

Example:

Procedure MyDisplay( cName, nAge, aColor, xValue )
   LOCAL Today := DATE()
   CHECK TYPE cName AS CHARACTER ,;
   nAge AS NUMERIC ,;
   aColor AS ARRAY ,;
   xValue AS USUAL ,;
   Today AS DATE
 ...
Return

Note: If any of the variable does not have the specified type an error message is displayed and the program is aborted.