未在Julia中定义的全局变量 [英] Global variable not defined in Julia

问题描述

以前曾在此处提出过类似的问题，但根据该问题的答案和Julia手册，以下.jl脚本应该可以使用.

A similar question has been previously asked here, but according to the answer to that question and the Julia manual, the following .jl script should work.

global myVar = spzeros(10,1);
myVar[3] = 1;

function test_base()
  test1();
end

function test1()
  myVar = [ i > 0 ? 2 : 0 for i in myVar] #doesn't work
end

我显式声明了全局变量，然后尝试在函数内部对其进行修改.但是，当我尝试运行函数test1()时，它说该变量未定义.

I explicitly declare a variable global and then try to modify it inside a function. However when I attempt to run the function test1(), it says that the variable is undefined.

julia> VERSION
v"0.3.5"

julia> include("test.jl")
test1 (generic function with 1 method)

julia> test_base()
ERROR: myVar not defined
 in test1 at /home/clifton/Julia/ca-1/test.jl:9
 in test_base at /home/clifton/Julia/ca-1/test.jl:5

我尝试了不同的方法，如果我只是在test1()中访问变量，它就会起作用，就像print(myVar);有人知道我在做什么错吗?

I've tried different things, and it does work if I just access the variable in test1(), like print(myVar); Does anyone know what I'm doing wrong?

推荐答案

我认为您需要将global放在需要访问全局变量的函数中.

I think you need to put global inside the function that needs to access the global variable.

以下对我有用:

myVar = spzeros(10,1);
myVar[3] = 1;

function test_base()
    test1();
end

function test1()
    global myVar
    myVar = [ i > 0 ? 2 : 0 for i in myVar] #doesn't work
end

输出:

julia> include("test.jl")
test1 (generic function with 1 method)

julia> test_base()
10-element Array{Int64,1}:
 0
 0
 2
 0
 0
 0
 0
 0
 0
 0

这篇关于未在Julia中定义的全局变量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！