I am trying to use Regex in my Ruby program to convert "|" character into a line breaker, so for example:
# convert("title|subtitle") => "title \n subtitle"
The regex I'm trying is the following:
title_params =~ s/\|/\\n/
But I kept getting errors saying that "|" is not recognized.
Regex is not needed for this simple problem:
=> puts "foo|bar".tr("|","\n")
foo
bar
I don't really know the syntax of your way of doing this but this works fine for me.
>> a = "title | subtitle"
=> "title | subtitle"
>> a.gsub(/\|/,"\n")
=> "title \n subtitle"
Related
When adding one escape character to string and printing the output does not replace escape character in the output string
indent = '\t'
message = 'Hello there'
message = "#{indent} #{message}"
puts(message)
From the above code output printed is as below
\t Hello there
What is wrong with this code? What is the way to achieve the intended output?
You have to use " instead ' in:
indent = '\t'
Look:
irb(main):001:0> indent = '\t'
=> "\\t"
irb(main):002:0> indent = "\t"
=> "\t"
So I'm having an issue replacing \" in a string.
My Objective:
Given a string, if there's an escaped quote in the string, replace it with just a quote
So for example:
"hello\"74" would be "hello"74"
simp"\"sons would be simp"sons
jump98" would be jump98"
I'm currently trying this: but obviously that doesn't work and messes everything up, any assistance would be awesome
str.replace "\\"", "\""
I guess you are being mistaken by how \ works. You can never define a string as
a = "hello"74"
Also escape character is used only while defining the variable its not part of the value. Eg:
a = "hello\"74"
# => "hello\"74"
puts a
# hello"74
However in-case my above assumption is incorrect following example should help you:
a = 'hello\"74'
# => "hello\\\"74"
puts a
# hello\"74
a.gsub!("\\","")
# => "hello\"74"
puts a
# hello"74
EDIT
The above gsub will replace all instances of \ however OP needs only to replace '" with ". Following should do the trick:
a.gsub!("\\\"","\"")
# => "hello\"74"
puts a
# hello"74
You can use gsub:
word = 'simp"\"sons';
print word.gsub(/\\"/, '"');
//=> simp""sons
I'm currently trying str.replace "\\"", "\"" but obviously that doesn't work and messes everything up, any assistance would be awesome
str.replace "\\"", "\"" doesn't work for two reasons:
It's the wrong method. String#replace replaces the entire string, you are looking for String#gsub.
"\\"" is incorrect: " starts the string, \\ is a backslash (correctly escaped) and " ends the string. The last " starts a new string.
You have to either escape the double quote:
puts "\\\"" #=> \"
Or use single quotes:
puts '\\"' #=> \"
Example:
content = <<-EOF
"hello\"74"
simp"\"sons
jump98"
EOF
puts content.gsub('\\"', '"')
Output:
"hello"74"
simp""sons
jump98"
I want to replace $word with another word in the following string:
"Hello $word How are you"
I used /\$(.*)/, /\$(.*)(\s)/ , /\$(.* \s)/. Due to *, I get the whole string after $, but I only need that word; I need to escape the space. I tried /s,\b, and few other options, but I cannot figure it out. Any help would be appreciated.
* is a greedy operator meaning it will match as much as it can and still allow the remainder of the regular expression to match. The token .* will greedily match every single character in the string. The regex engine will then advance to the next token \s which matches the last whitespace before the word "you" in the string given you a result of word How are.
You can use \S in place of .* which matches any non-whitespace characters.
\$\S+
Or to simply match only word characters, you can use the following:
\$\w+
If you only want to replace "$world" using a regex, try this:
"Hello $word How are you".gsub(/\$word/, 'other_word')
Or:
"Hello $word How are you".sub('$word',"*")
You can read more for gsub here: http://www.ruby-doc.org/core-2.2.0/String.html#method-i-gsub
Substituting placeholder words for other words is usually not done with a regex but with the % method and a hash:
h = {word: "aaa", other_word: "bbb"}
p "Hello %{word} How are you. %{other_word}. Bye %{word}" % h
# => "Hello aaa How are you. bbb. Bye aaa"
Consider:
>> string = "Hello $word How are you"
=> "Hello $word How are you"
>> replace_regex = /(?<replace_word>\$\w+)/
=> /(?<replace_word>\$\w+)/
>> string.gsub(replace_regex, "Bob")
=> "Hello Bob How are you"
>> string.match(replace_regex)[:replace_word]
=> "$word"
Note:
replace_word is the regex with a named capture group.
I'm trying to do something like the following. Let's say i have the following string:
"some string"
And i wanted to replace the space with a \1. However, wether i use single or double quote, i dont get the result:
"some string".gsub(" ", "\1") => "somestring"
"some string".gsub(" ", '\1') => "somestring"
"some string".gsub(" ", '\\1') => "somestring"
What i want is:
"some\1string"
Any suggestions?
This is only annoying because \1 through \9 are reserved for use in substitutions.
A possible solution is:
"some string".gsub(" ", '\\\\1')
It's kind of ugly, but it works.
An alternative is to use the block style where substitution isn't performed:
"some string".gsub(" ") { '\1' }
Remember that the output will be "some\\1string" because backslash is represented as \\ inside a double-quoted string. If you print it out you will get a single backslash.
This is also possible:
s = "some string"
p s.split.join('\1') # "some\\1string"
Here's something I often do when programming:
code = ''
code << "next line of code #{something}" << "\n"
code << "another line #{some_included_expression}" << "\n"
Is there some better way than having << "\n" or + "\n" on every line? This seems quite inefficient.
I'm interested in Ruby solutions, in particular. I'm thinking something like
code = string.multiline do
"next line of code #{something}"
"another line #{some_included_expression}"
end
If you're looking to build a block of text, the easy way to do it is to just use the % operator. For example:
code = %{First line
second line
Third line #{2 + 2}}
'code' will then be
"First line\n second line\n Third line 4"
This would be one way:
code = []
code << "next line of code #{something}"
code << "another line #{some_included_expression}"
code.join("\n")
Use <<- operator:
code = <<-CODE
var1 = "foo"
var2 = "bar"
CODE
It would work for you to just embed ...\n" in your strings, I suppose. Here is a fun way to do it:
class String
def / s
self << s << "\n"
end
end
then
f = "" # => ""
f / 'line one' # => "line one\n"
f / 'line two' # => "line one\nline two\n"
f / 'line three' # => "line one\nline two\nline three\n"
This would enable something like:
"" / "line 1" / "line 2" / "line 3" # => "line 1\nline 2\nline 3\n"
Or even:
f/
"line one"/
"line two"/
"line three" # => "line one\nline two\nline three\n"
Here's a method presented here:
str = <<end.margin
|This here-document has a "left margin"
|at the vertical bar on each line.
|
| We can do inset quotations,
| hanging indentions, and so on.
end
This is accomplished by using this:
class String
def margin
arr = self.split("\n") # Split into lines
arr.map! {|x| x.sub!(/\s*\|/,"")} # Remove leading characters
str = arr.join("\n") # Rejoin into a single line
self.replace(str) # Replace contents of string
end
end
I guess the question with this is: does the lack of portability / presence of monkey patching make this solution bad.
What's wrong with:
code = "next line of code #{something}\n"+
"another line #{some_included_expression}"
You could place your multi-line text in a file, and use ERB to parse it (note ERB is included with Ruby)
require 'erb'
multi_line_string = File.open("multi_line_string.erb", 'r').read
template = ERB.new(multi_line_string)
template.result(binding)
(ERB can access variables from a Binding, an object that provides access to the instance methods and variables that are owned by another object. By setting it to "binding" it points to itself)
Documentation here.