Julia 在for循环中重复使用的多个输出

我使用的是Julia，我设计了一个for循环，它在一个循环中获取函数的输出，并在下一个循环中使用它们作为该函数的输入（一次又一次）。当我运行这段代码时，Julia会标记一个“未定义”错误，但是，如果我在调试模式下运行代码，它会完美地执行。例如，代码如下所示：

function do_command(a,b,c,d)
   a = a + 1
   b = split(b, keepempty=false)[1]
   c = split(b, keepempty=false)[1]
   if a == 1000
      d = true
   else
      d = false
   end
   return a, b, c, d
end

for ii in 1:length(x)
   if ii == 1
      a = 0
      b = "string something"
      c = ""
      d = false
   end
   a,b,c,d = do_command(a,b,c,d)
   if d == true
      print(string(b))
      break
   end
end

function do_command(a,b,c,d)
   a = a + 1
   b = split(b, keepempty=false)[1]
   c = split(b, keepempty=false)[1]
   if a == 1000
      d = true
   else
      d = false
   end
   return a, b, c, d
end

# Let's create a local scope: it's good practice to avoid global variables
let
    # All these variables are declared in the scope introduced by `let`
    a = 0
    b = "string something"
    c = ""
    d = false

    for ii in 1:10 #length(x)
        # now these names refer to the variables declared in the enclosing scope
        a,b,c,d = do_command(a,b,c,d)
        if d == true
            print(string(b))
            break
        end
    end
end

---

我做错了什么？

您的代码的一个问题是

for

为循环的每个迭代引入了一个新的范围。也就是说：在迭代1时在循环体中创建的变量

a

与在迭代2时在循环体中创建的变量

a

不同

为了解决您的问题，您应该在循环外部声明变量，以便在每次迭代中，从循环体中对它们的引用实际上会引用封闭范围中的相同变量

我会这样说：

function do_command(a,b,c,d)
   a = a + 1
   b = split(b, keepempty=false)[1]
   c = split(b, keepempty=false)[1]
   if a == 1000
      d = true
   else
      d = false
   end
   return a, b, c, d
end

for ii in 1:length(x)
   if ii == 1
      a = 0
      b = "string something"
      c = ""
      d = false
   end
   a,b,c,d = do_command(a,b,c,d)
   if d == true
      print(string(b))
      break
   end
end

function do_command(a,b,c,d)
   a = a + 1
   b = split(b, keepempty=false)[1]
   c = split(b, keepempty=false)[1]
   if a == 1000
      d = true
   else
      d = false
   end
   return a, b, c, d
end

# Let's create a local scope: it's good practice to avoid global variables
let
    # All these variables are declared in the scope introduced by `let`
    a = 0
    b = "string something"
    c = ""
    d = false

    for ii in 1:10 #length(x)
        # now these names refer to the variables declared in the enclosing scope
        a,b,c,d = do_command(a,b,c,d)
        if d == true
            print(string(b))
            break
        end
    end
end

---

您的示例中缺少了

x

，但我想这只是一个拷贝粘贴问题，而不是您真正的问题。。。