I learned that gets creates a new line and asks the user to input something, and gets.chomp does the same thing except that it does not create a new line. gets must return an object, so you can call a method on it, right? If so, lets name that object returned by gets as tmp, then you can call the chomp method of tmp. But before gets returns tmp, it should print a new line on the screen. So what does chomp do? Does it remove the new line after the gets created it?
Another way to re-expound my question is: Are the following actions performed when I call gets.chomp?
gets prints a new line
gets returns tmp
tmp.chomp removes the new line
User input
Is this the right order?
gets lets the user input a line and returns it as a value to your program. This value includes the trailing line break. If you then call chomp on that value, this line break is cut off. So no, what you have there is incorrect, it should rather be:
gets gets a line of text, including a line break at the end.
This is the user input
gets returns that line of text as a string value.
Calling chomp on that value removes the line break
The fact that you see the line of text on the screen is only because you entered it there in the first place. gets does not magically suppress output of things you entered.
The question shouldn't be "Is this the right order?" but more "is this is the right way of approaching this?"
Consider this, which is more or less what you want to achieve:
You assign a variable called tmp the return value of gets, which is a String.
Then you call String's chomp method on that object and you can see that chomp removed the trailing new-line.
Actually what chomp does, is remove the Enter character ("\n") at the end of your string. When you type h e l l o, one character at a time, and then press Enter gets takes all the letters and the Enter key's new-line character ("\n").
1. tmp = gets
hello
=>"hello\n"
2. tmp.chomp
"hello"
gets is your user's input. Also, it's good to know that *gets means "get string" and puts means "put string". That means these methods are dealing with Strings only.
chomp is the method to remove trailing new line character i.e. '\n' from the the string.
whenever "gets" is use to take i/p from user it appends new line character i.e.'\n' in the end of the string.So to remove '\n' from the string 'chomp' is used.
str = "Hello ruby\n"
str = str.chomp
puts str
o/p
"Hello ruby"
chomp returns a new String with the given record separator removed from the end of str (if present).
See the Ruby String API for more information.
"gets" allows user input but a new line will be added after the string (string means text or a sequence of characters)
"gets.chomp" allows user input as well just like "gets", but there is
not going to be a new line that is added after the string.
Proof that there are differences between them:
Gets.chomp
puts "Enter first text:"
text1 = gets.chomp
puts "Enter second text:"
text2 = gets.chomp
puts text1 + text2
Gets:
puts "Enter first text:"
text1 = gets
puts "Enter second text:"
text2 = gets
puts text1 + text2
Copy paste the code I gave you, run and you will see and know that they are both different.
For example:
x = gets
y = gets
puts x+y
and
x = gets.chomp
y = gets.chomp
puts x+y
Now run the two examples separately and see the difference.
Related
Here is my short program
def def1()
x = 1
puts x
end
def def2()
y = 2
puts y
end
puts "some text #{def1}"
puts "some text #{def2}"
The outcome of this example...
1
some text
2
some text
I don't understand why this puts in this order and not "sometext" first.
Because the string is created first, which means calling def1, and then the whole string is passed into puts.
We can expand puts "some text #{def1}" out to understand.
string = "some text " + def1.to_s
puts string
As you can see, def1 is called to create the string. def1 prints out 1 itself, it does not return anything (it returns nil). Then the whole string is printed.
That's how all function calls work. The arguments are evaluated, the the function is called.
You'd need to call def1 after printing the prefix.
print "some text "
def1
This is a reason why it's often better to have a function return a value rather than print it itself.
In order to print the string, puts has to know what the string is. In order to know what the string is in this particular line:
puts "some text #{def1}"
Ruby has to call def1 first. def1, in turn, calls puts to print something.
I'm trying to receive multiple paragraphs at once from a user.
I've tried using gets, but it doesn't seem to be working... it discards the second paragraph:
#The code:
print("Paste your text here: ")
.. essay = gets
.. puts(essay)
# Getting user imput (the second sentance is a separate paragraph)
Paste your text here: I like cake.
It makes me happy.
# What the computer did for puts(essay):
I like cake.
=> nil
I expected the result to be something like this:
"I like cake.\nIt makes me happy.\n"
But it gave me "I like cake." instead.
How could I end up with my expected result?
Add paragraphs to a string until the input consists of a empty line:
str = ""
para = "init"
str << (para = gets) until para.chomp.empty? #or para == "\n"
p str
Here's an alternative, with a slightly different logic
def getps
save, $/ = $/, "\n\n"
gets.chomp
ensure
$/ = save
end
str = getps
The global variable $/ is what Ruby uses to find out what line end is. gets gets things till line end. If we tell Ruby that line end is two newlines, then gets waits till we have two newlines in a row till it exits. Since we don't need them, we'll just chomp them off. The rest of the code is just to ensure that $/ gets restored properly afterwards so normal gets is not messed up forever.
What is the difference between these three:
gets - it gets a line with '\n'
gets.chomp - it gets a line, but removes '\n'
Is that correct? What about gets.chomp! ?
gets - it gets a string with '\n' at the end ( or better to say the line separator $/ at the end) , then #chomp removes the \n ( or I would say the default value of $/),and give you a new string. But #chomp! did the same change in the receiver or the source string itself, on which you called #chomp! method.
Note : #chomp! is a bang version of #chomp.
Okay,
I am doing the codeacademy ruby track and I am not stock with the problem.
I can make it works now, but I don't understand why it works.
instructions for exercise:
Let's start simple: write an .each loop that goes through words and just prints out each word it finds.
I have broken the problem into steps to try to understand why it works
but I am very confused.
My code for the problem is:
puts "Text to search through: " #ask user for input
text = gets.chomp
#store the user's input into the variable text
puts "Text to be reducted: "
#ask the user for input
redact = gets.chomp
#store the user's input into the variable redact
words = text.split(" ")
=begin
split the user's input into the variable words
store that input into the variable words
=end
words.each do |word|
=begin
creates a placeholder for the user's input
then attach an expression to the input stored in
the variable words one at a time. The variable
words holds the value of the variable text
=end
if word != redact
=begin
if word (which now holds the value of words that's
stored in the variable text, and which is the user's input)
is not equal to the value of the variable redact do something
=end
word = word + " "
=begin
increment the value of word by an empty space
why do I need to increment the value of word by an empty space?
=end
print "#{word}" #print the value of the variable word
else
print "REDACTED" #otherwise, print the value redacted
end
end
The program works if I use a string separated by an space and only if I change
word = word + ""
instead of
word = word + " "
I would truly appreciate if someone break it down for me, step by step.
I created a video of it for a more visual explanation of it.
here is the link: ruby redaction video
thank you.
The problem in your video is that "nelson" is not the same as "nelson ", and the Codeacademy scoring doesn't see a match when you append a space to the word before printing it.
I am reading this problem in July 2019..
So anybody who is reading this problem and getting confused with the below part asked by the user:
word = word + " "
=begin
increment the value of word by an empty space
why do I need to increment the value of word by an empty space?
So the answer is that the + sign is not for incrementing the value it's for adding a space and the + sign is used as string concatenator. So it has been placed there so that whatever words are being searched and displayed, they have a space between them.
I am trying to create a program that alphabetizes a users' word entries. However, inspection of the users entries reveals that ruby is for some reason adding a newline character to each word. For instance, If i enter Dog, Cat, Rabbit the program returns ["Cat\n", "Dog\n", "Rabbit\n"] How do i prevent this from happening?
words = []
puts "Enter a word: "
until (word = gets).to_s.chomp.empty?
puts "Enter a word: "
words << word
end
puts words.sort.inspect
Change your code to:
until (word = gets.chomp).empty?
The way you're doing it now:
(word = gets).to_s.chomp.empty?
gets the string from the keyboard input, but it isn't returned to your code until the user presses Return, which adds the new-line, or carriage-return + new-line on Windows.
to_s isn't necessary because you're already getting the value from the keyboard as a string.
chomp needs to be tied to gets if you want all the input devoid of the trailing new-line or new-line/carriage-return. That will work fine when testing for empty?.
Ruby 2.4 has a solution for this:
input = gets(chomp: true)
# "abc"