From terminal to Ruby (standard input / output)

!macOS-11.1!ruby-2.7.2p137

Preface (Introduction)

This article is related to Part 5 of the Special Lecture on Multiscale Simulation. We will proceed according to Chart Ruby.

This time, we will learn the standard input / output of Ruby according to Chart type ruby-I (puts).

Ruby

Standard input / output

First of all, familiar

hello world.

Create a program that returns this string.

1. String output

There are multiple functions for outputting strings in Ruby.

Typical ones

 | method |Explanation|new line|
 |:-------|:-----------------------------------------------------------------------------------|:----|
 | print  |Argument object is converted to a character string and output to standard output.                                        | ×  |
 | puts   |Convert the argument object to a character string, add a line break, and output to standard output..                            | ○  |
 | p      |puts for debug,Raw strings are output to standard output without being processed even if they are escaped..| ○  |
 | pp     |p pretty print,Standard output is easier to understand than p. require'pp'Is necessary.               | ○  |

Let's make it now.

```ruby:hello_world.rb
print "hello world1"
puts "hello world2"
p "hello world3"
pp "hello world4"
```

The output is

```
> ruby hello_world.rb
```

```
hello world1hello world2
"hello world3"
"hello world4" 
```

2. Enter a character string

Next to the output is the input!

So, next, use the gets method to say hello to your favorite string.

```ruby:hello_name.rb
name = gets
puts "hello " + name
```

The output is

```
> ruby hello_name.rb
```

```
W
hello W
```

Now that I want to work with the CLI, I want to use ARGV [0].

```ruby:hello_name.rb
puts "hello #{ARGV[0]}"
```

The output is

```
> ruby hello_name.rb W
-> hello W
```

Similar

Try writing standard output to a suitable file using Redirect>.

> ruby hello_name.rb Woo > hello_name.txt

Check if it was output properly

> cat hello_name.txt
-> hello Woo