Apple-2-SW/EightBall
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'Naked' array name evaluates to address

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Bobbi Webber-Manners 2018-05-03 20:02:20 -04:00 committed by GitHub
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@ -350,11 +350,23 @@ EightBall also implements 'star operators' for pointer dereferencing which will
#### Address-of Operator
The `&` prefix operator returns a pointer to a variable which may be used to read and write the variable's contents. The operator may be applied to scalar variables, whole arrays and individual elements of arrays.
word w = 123;
word A[10] = 0;
word w = 123
word A[10] = 0
pr.dec &w; ' Address of scalar w
pr.dec &A; ' Address of start of array A
pr.dec &A[2] ' Address of third element of array A
Note also that for arrays, evaluating just the array name with no index give the address of the start of the array. (This trick enables the array pass-by-reference feature to work.)
The following code will print "ALL THE SAME" on the console:
word A[10] = 0
word a1 = A
word a2 = &A
word a3 = &A[0]
if ((a1 == a2) && (a1 == a3))
pr.msg "ALL THE SAME"; pr.nl
endif
#### 'Star Operators'
EightBall provides two 'star operators' which dereference pointers in a manner similar to the C star operator. One of these (`*`) operates on word values, the other (`^`) operates on byte values. Each of the operators may be used both for reading and writing through pointers.