BBC BASIC Programmers' Reference

Simple Registry Usage

By JGH, Feb-2007.

The registry is a repository of data maintained by Windows, which holds various information. An application can store configuration or other information from one session to the next within the HKCU/Software/MyPublisher/MyApplication part of the registry, where MyPublisher and MyApplication are set appropriately.

The registry can store various types of data, such as strings, integers, multiple strings, binaries, but you can do simple registry access if you just use string entries.

An example program FredProg from BloggSoft can read settings using code similar to the following:

        KeyRoot$="Software\BloggSoft\FredProg\"
 
        LastSaved$=FNReg_Rd(KeyRoot$+"LastSaved")
        LoadPath$ =FNReg_Rd(KeyRoot$+"LoadPath")

It can later update the registry entries using the following code:

        KeyRoot$="Software\BloggSoft\FredProg\"
 
        PROCReg_Wr(KeyRoot$+"LastSaved",LastSave$)
        PROCReg_Wr(KeyRoot$+"LoadPath",LoadPath$)

You should ensure KeyRoot$ is formed in the above format to ensure consistency and to ensure the registry names are unique to your application.

The example code uses the Reg_Rd() and Reg_Wr() functions in the Reg BASIC library, and listed here:

        DEF FNReg_Rd(Key$)
        LOCAL K%,R%,L%,T%,B%,Item$,Value$
        Item$=Key$:REPEAT:K%=INSTR(Item$,"\"):IFK%:Item$=MID$(Item$,K%+1)
        UNTILK%=0:Key$=LEFT$(Key$,LENKey$-LENItem$-1)
        SYS "RegOpenKeyEx",&80000001,Key$,0,&20001,^K% TO R%
        IF R%=0 THEN
          SYS "RegQueryValueEx",K%,Item$,0,^T%,0,^L%:DIM B% LOCAL L%
          SYS "RegQueryValueEx",K%,Item$,0,^T%,B%,^L% TO R%
          IF R%=0:Buf%?(L%-1)=13:Value$=$B%
          SYS "RegCloseKey",K%
        ENDIF
        =Value$
 
        DEF PROCReg_Wr(Key$,Value$)
        LOCAL K%,D%,R%,Item$
        Item$=Key$:REPEAT:K%=INSTR(Item$,"\"):IFK%:Item$=MID$(Item$,K%+1)
        UNTILK%=0:Key$=LEFT$(Key$,LENKey$-LENItem$-1)
        SYS "RegCreateKeyEx",&80000001,Key$,0,"",0,&F003F,0,^K%,^D% TO R%
        IF R%=0 THEN
          SYS "RegSetValueEx",K%,Item$,0,1,Value$,LENValue$+1
          SYS "RegCloseKey",K%
        ENDIF
        ENDPROC