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The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

  ◄Data Types►   ◄Type Conversions►   ◄Contents►   ◄Index►
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Type Conversion
 
When necessary, BASIC converts a numeric constant from one type to another,
according to the following rules:
 
  ■ If a numeric constant of one type is set equal to a numeric variable of
    a different type, the numeric constant is stored as the type declared
    in the variable name, as in the following example:
 
      A% = 23.42
      PRINT A%
 
      Output:
 
      23
 
    If a string variable is set equal to a numeric value, or vice versa, an
    error message is generated that reads: "Type Mismatch."
 
  ■ During expression evaluation, the operands in an arithmetic or
    relational operation are converted to the same degree of precision,
    that of the most precise operand, as each operation is performed. Also,
    the result of an arithmetic operation is returned to the final degree
    of precision, as in the following example:
 
      X% = 2 : Y! = 1.5 : Z# = 100
      A! = X% / Y!
      PRINT A! * Z#
 
      Output:
 
      133.3333373069763
 
    Although the preceding result is displayed in double precision (because
    of the double-precision variable Z#), it has only single-precision
    accuracy, because the assignment to A! forced the result of X% / Y! to
    be reduced to single-precision accuracy. This explains the
    nonsignificant digits (73069763) after the fifth decimal place.
    Contrast this with the output from the following example in which the
    intermediate result of X% / Y! is retained in double precision:
 
      X% = 2 : Y# = 1.5 : Z# = 100
      PRINT X% / Y# * Z#
 
      Output:
 
      133.3333333333333
 
  ■ Logical operators such as AND and NOT convert their operands to long
    integers if necessary. Operands must be in the range -2,147,483,648 to
    +2,147,483,647 or an "Overflow" error message is generated.
 
  ■ When a floating-point value is converted to an integer, the fractional
    portion is rounded, as in this example:
 
      Total% = 55.88
      PRINT Total%
 
      Output:
 
      56