Counted loops in turing language

Question

% calculates the population of a city from year 2000 to 2020

var popstart : int := 80000
var popgrowth : real
var popend : real
var growthrate : real := 0.03

% popgrowth := popstart * growthrate
    for i : 2000..2020 by 1
popgrowth := popstart * growthrate
end for

put "year  population"
put "====  =========="
put  i, "  ", popgrowth

when I run the program, i get the error variable "i has not been declared" when I declare i as a variable, I get the error "i has already been declared"

the output should look something like this:

year population
==== ==========
2000 xxxxxxxxxx ~ 2020 XXXXXXXXXX

here's a similar, but much simpler program, where i was successful in doing what i'm attempting to do in the program above.

for i : 4 .. 19 by 3
    put i
end for

HELP PLEASE! and thanks in advance!

Answer 1

I don't know much about Turing, but I suspect that the for i... is an implicit declaration of i.

So, I don't know how you could fix it, but you could get around it by doing this:

var last_year: int
for i : 2000..2020 by 1
    popgrowth := popstart * growthrate
    last_year = i
end for

put "year  population"
put "====  =========="
put  last_year, "  ", popgrowth