朱莉娅传递参数，阅读命令行 [英] Julia passing arguments, reading the command line

问题描述

我试图提示我的.jl文件用户输入用户输入的多个目的地.

I am trying to prompt the user of my .jl file to enter user entered multiple destinations.

基本上，我需要用户输入&输出.我知道在Java中，您将使用扫描仪，或者在命令行中编译时接受参数.无论哪种选择我都很好.通过查看Julia文档，我认为我可以完成将变量分配给readline函数的第一种方法.

Basically I need the user to give an input & an output. I know in java you would use a scanner, or accept arguments when it is compiled in the command line. I am fine with either option. From what I have found looking through the Julia Documentation I think I could accomplish the first way of assigning a variable to the readline function.

(String)in = (String)Readline(STDIN)

据我了解，变量"in"现在应包含用户输入的字符串.我在编译.jl代码时遇到错误，因为我的命令提示符不会停止读取用户输入，而只是完成读取.jl代码.

From my understanding the variable 'in' should now contain a String of the user's input. I am encountering an error, in that when I compile my .jl code, because my command prompt does not stop to read user input, and just finishes reading the .jl code.

推荐答案

问题代码中要注意的第一项是:

The first item to note in the code in your question is:

(String)in = (String)Readline(STDIN)

Julia 1.0.0现在使用stdin而不是STDIN.

Julia 1.0.0 now uses stdin instead of STDIN.

接下来，(String)类型转换不是您在Julia中需要或不想做的事情.

Next, the (String) typecasting is not something you need or want to do in Julia.

因此您的代码可以读取(尽管会出现错误):

Thus your code could read (though we get an error):

julia> in = readline(stdin)
This is a test.
ERROR: cannot assign variable Base.in from module Main

因此，变量in与Julia Base.in变量冲突.只需使用另一个变量名即可.

So variable in is in conflict with a Julia Base.in variable. Just use a another variable name.

julia> response = readline(stdin)
This is a test.
"This is a test"

此代码现在可以运行，但是没有提示.您的答案提供了一个示例输入功能，并带有如下定义的提示:

This code is now working, but it has no prompt. Your answer provides an example input function with a prompt which you defined like this:

julia> function input(prompt::AbstractString="")
           print(prompt)
           return chomp(readline())
       end
input (generic function with 2 methods) 

chomp函数从输入字符串中删除单个尾随的\n换行符. Docs 此处.

The chomp function removes a single trailing \n newline character from the input string. Docs here.

此处使用该功能的示例:

Example use of the function here:

julia> input_file = input("Please enter input file name: ")
Please enter input file name: Data.txt
"Data.txt"

julia> output_file = input("Please enter output file name: ")
Please enter output file name: Output.txt
"Output.txt"

命令行Args方法

作为 docs 指出，仅打印出给脚本的参数，您可以执行以下操作:

As the docs point out, to just print out the arguments given to a script, you can do something like this:

println("Arguments passed to ", PROGRAM_FILE, ":")
for arg in ARGS
    println(arg)
end

以下是在Windows命令行上运行的上述代码的示例:

Here is an example of above code running on the Windows command line:

c:\OS_Prompt>julia PrintArgs.jl Data.txt Output1.txt Output2.txt Output3.txt
Arguments passed to PrintArgs.jl:
Data.txt
Output1.txt
Output2.txt
Output3.txt

您还可以打印出脚本文件名，如PrintArgs.jl.

You can also print out the script file name as shown, PrintArgs.jl.

这篇关于朱莉娅传递参数，阅读命令行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！