BBC BASIC Programmers' Reference

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=====Using DATA statements in libraries=====

//by Richard Russell, March 2011//\\ \\  Because you cannot use **line numbers** or **labels** in libraries (or other [[http://www.bbcbasic.co.uk/bbcwin/manual/bbcwin5.html#install|INSTALLed]] modules), the conventional forms of the [[http://www.bbcbasic.co.uk/bbcwin/manual/bbcwin7.html#restore|RESTORE]] statement cannot be used. At first sight it might appear that this precludes the use of [[http://www.bbcbasic.co.uk/bbcwin/manual/bbcwin4.html#data|DATA]] statements in libraries, but in fact they can be used by means of the //relative// version **RESTORE +**.\\ \\  For example the following code could be placed in a library:\\ 
<code bb4w>
        DEF PROCrestore
        RESTORE +1
        ENDPROC
        DATA Here,are,some,data,items,in,a,library
        DATA Here,is,some,more,data
</code>
Calling **PROCrestore** moves the data pointer so that the next items to be [[http://www.bbcbasic.co.uk/bbcwin/manual/bbcwin7.html#read|READ]] will be taken from the subsequent DATA statements:\\ 
<code bb4w>
        PROCrestore
        READ A$,B$,C$,D$
</code>
(this code could be in the main program or in a library).\\ \\  Note the use of **RESTORE +1** rather than **RESTORE +2**, as might superficially seem more correct. This ensures that the code will work correctly even if the library is crunched using the **concatenate lines** option (resulting in the **ENDPROC** being moved onto the same line as the **RESTORE**).\\ \\  If you find that disconcerting you could always move the **ENDPROC** until after the **DATA** statements:\\ 
<code bb4w>
        DEF PROCrestore
        RESTORE +1
        DATA Here,are,some,data,items,in,a,library
        DATA Here,is,some,more,data
        ENDPROC
</code>