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listvariable-assignmentrebolred-lang

Why variables not altering from a loop in Red language

I want to alter a series of variables from a loop, but the following code is not working: 

a: 10
b: 20
c: 30
print reduce [a b c]              ; output is 10 20 30 as expected

varnames: [a b c]                 ; make a series of variables
foreach i varnames [              ; loop to convert each to 0
    i: 0
]

print "After conversion loop: "
print reduce [a b c]              ; values are still 10 20 30 (expected 0 0 0)

After running this code, I'd expect the values of a, b, c to be changed, but they're not:

>> print reduce [a b c]   
10 20 30

Where is the problem?

Solution 
  • >> set varnames: [a b c] [10 20 30]
== [10 20 30]

>> foreach i varnames [set i 0]
== 0

>> reduce varnames
== [0 0 0]

    You've given i a value from the loop, and then given it a different value of 0, but you actually haven't altered the word that i referred to. set allows you to do this.