4.6: Variable Scope

If you are using the command line julia (also called the REPL) or iJulia, then entering x=6 will create x as a global variable, even without saying so explicitly. If we consider the factorial function above:

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function fact(n::Integer) 
  prod=1
  for i=1:n 
    prod *= i
  end
  prod
end

function fact(n::Integer) 
  prod=1
  for i=1:n 
    prod *= i
  end
  prod
end

then recall that n is the function argument and the variable prod is actually declared locally implicitly and it is good form to say it is local by

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function fact(n::Integer) 
  local prod=1
  for i=1:n
    prod *= i 
  end
  prod
end

function fact(n::Integer) 
  local prod=1
  for i=1:n
    prod *= i 
  end
  prod
end

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2*prod

2*prod

Local and Global Variables

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x=3
function f()
  local x=2
  x
end
f()

x=3
function f()
  local x=2
  x
end
f()

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x

x

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x=3
function g()
  global x=2
  x
end
g()

x=3
function g()
  global x=2
  x
end
g()

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x

x