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128 lines
4.9 KiB
Markdown
[#]: collector: (lujun9972)
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[#]: translator: ( )
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[#]: reviewer: ( )
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[#]: publisher: ( )
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[#]: url: ( )
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[#]: subject: (Learn Julia by coding a game)
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[#]: via: (https://opensource.com/article/20/12/julia)
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[#]: author: (Moshe Zadka https://opensource.com/users/moshez)
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Learn Julia by coding a game
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======
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Writing the same application in multiple languages is a great way to
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learn new ways to program.
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![woman on laptop sitting at the window][1]
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Most programming languages have certain things in common, such as:
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* Variables
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* Expressions
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* Statements
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These concepts are the basis of most programming languages. Once you understand them, you can start figuring the rest out.
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Programming languages usually share some similarities. Once you know one programming language, you can learn the basics of another by recognizing its differences.
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A good tool for learning a new language is by practicing with a standard program. This allows you to focus on the language, not the program's logic. I'm doing that in this article series using a "guess the number" program, in which the computer picks a number between one and 100 and asks you to guess it. The program loops until you guess the number correctly.
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This program exercises several concepts in programming languages:
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* Variables
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* Input
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* Output
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* Conditional evaluation
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* Loops
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It's a great practical experiment to learn a new programming language.
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### Guess the number in Julia
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According to [Julia][2]'s website, the language "is dynamically typed, feels like a scripting language, and has good support for interactive use." It "was designed from the beginning for high performance. Julia programs compile to efficient native code for multiple platforms via LLVM."
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You can explore Julia by writing a version of the "guess the number" game.
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Here is my implementation:
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```
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random = rand(1:100)
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println("Guess a number between 1 and 100")
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while true
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data = readline()
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if data == ""
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println("goodbye")
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break
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end
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guess = parse(Int64, data)
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if guess < random
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println("Too low")
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elseif guess > random
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println("Too high")
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else
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println("That's right!")
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break
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end
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```
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To assign a value to a variable, list the variable's name followed by the `=` sign. For example, the statement `random = 0` assigns a zero value to the `random` variable.
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The first line of the script reads the result of the function `rand()` and assigns it to the variable called `random`. The function takes a single argument: a range. In this case, the range is `1:100`, making the game just challenging enough.
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You can also prompt the user to enter a value using the `readline()` function. If you write `data = readline()`, Julia waits for the user to enter some text, then stores that value in the guess variable.
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The next step is to convert `data` to an integer type. In this case, use `Int64`, a 64-bit integer type. The result of the `parse` function is stored in a variable `guess`.
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Julia supports conditional expressions and flow control like loops. In the "guess the number" game, Julia continues looping as long as the guess value is not equal to `random`.
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If the guess is less than the random number, Julia prints `Too low`, and if the guess is greater than the number, Julia prints `Too high`.
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### Sample output
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Now that you've written your Julia program, run it to play the "guess the number" game. Every time you run the program, Julia will pick a different random number, so you need to guess until you find the correct number:
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```
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$ julia guess.jl
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Guess a number between 1 and 100
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50
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Too high
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30
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Too high
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20
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Too high
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10
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Too low
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15
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Too high
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13
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Too low
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14
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That's right!
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```
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This "guess the number" game is a great introductory program for learning a new programming language because it exercises several common programming concepts in a pretty straightforward way. By implementing this simple game in different programming languages, you can demonstrate some core concepts of the languages and compare their details.
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Do you have a favorite programming language? How would you write the "guess the number" game in it? Follow this article series to see examples of other programming languages that might interest you!
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/20/12/julia
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作者：[Moshe Zadka][a]
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选题：[lujun9972][b]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://opensource.com/users/moshez
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[b]: https://github.com/lujun9972
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[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/lenovo-thinkpad-laptop-window-focus.png?itok=g0xPm2kD (young woman working on a laptop)
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[2]: https://julialang.org/
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