LOCAL Keyword

LOCAL variable-name = expression

Declares or modifies a local variable whose value is accessible only within the current PROC, FN or GOSUB call.
When that call returns, variables marked LOCAL are discarded.

Remarks

LOCAL must appear with an assignment.

LOCAL without = expression is not valid.

Parameters to a PROC or FN are already local.

You assign to parameters normally (no LOCAL needed or wanted).

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Behaviour

• A LOCAL assignment creates/uses a local variable for this call only.
  
• If a global of the same name exists, LOCAL shadows it for this call.
  
• Inside the body, an assignment without LOCAL refers to the global variable of that name (if any), not the local created with LOCAL.
  Therefore, if you intend to keep updating the local value, prefix each assignment with LOCAL.

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Examples

Create and update a local in a procedure

DEF PROCsum_demo
    LOCAL TOTAL = 0
    FOR I = 1 TO 3
        LOCAL TOTAL = TOTAL + I
    NEXT
    PRINT "TOTAL = "; TOTAL
ENDPROC
 
PROCsum_demo

Modify a parameter (no LOCAL needed)

DEF PROCincrement(N)
    N = N + 1
    PRINT "Inside PROC, N = "; N
ENDPROC
 
X = 10
PROCincrement(X)
PRINT "After call, X = "; X

Shadowing a global, and what happens without LOCAL

X = 5
 
DEF PROCwork
    LOCAL X = 99
    PRINT "Local X = "; X
    X = 100          REM this updates the GLOBAL X, not the local one
    PRINT "Local X still = "; X
ENDPROC
 
PROCwork
PRINT "Global X now = "; X

Use inside a GOSUB subroutine (line numbers permitted)

10 GOSUB 1000
20 END
 
1000 LOCAL T = 1
1010 LOCAL T = T + 1
1020 PRINT "T = "; T
1030 RETURN

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See also:
DEF · PROC · ENDPROC · FN · GOSUB