MID$ Function
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 Action

 Returns a substring of a string.


 Syntax

  MID$( stringexpression$,  start%,  length%)

 Remarks


 The  MID$ function uses the following arguments.

-----------------------------------------------------------------------------
 Argument                                Description
 ----------------------------------------------------------------------------
  stringexpression$                      The string expression from which
                                         the substring is extracted. This
                                         can be any string expression.

  start%                                 The character position in
                                         stringexpression$ where the
 Argument                                Description
 ----------------------------------------------------------------------------
                                         stringexpression$ where the
                                         substring starts.

  length%                                The number of characters to
                                         extract.





 The arguments  start% and  length% must be between 1 and 32,767, inclusive.
 If  length% is omitted or if there are fewer than  length% characters in the
 string (including the  start% character), the  MID$ function returns all
 characters from the position  start% to the end of the string.

 If  start% is greater than the number of characters in  stringexpression$,
 MID$ returns a null string.

 Use the  LEN function to find the number of characters in
 stringexpression$.


 See Also

  LEFT$,  LEN,  MID$ Statement,  RIGHT$


 Example

 The following example converts a binary number to a decimal number. The
 program uses the  MID$ function to extract digits from the binary number
 (input as a string).

 INPUT "Binary number = ", Binary$' Input binary number as string.

 Length = LEN(Binary$)' Get length of string.

 Decimal = 0

 FOR K = 1 TO Length

    Digit$ = MID$(Binary$, K, 1) ' Get digit from string.

    IF Digit$ = "0" OR Digit$ = "1" THEN' Test for binary digit.

       Decimal = 2 * Decimal + VAL(Digit$)' Convert digits to numbers.

    ELSE

       PRINT "Error--invalid binary digit. "; Digit$

       EXIT FOR

    END IF

 NEXT

 PRINT "Decimal number =" Decimal