I make a string and I ask the user to insert a name. I need three of the letters they wrote
print "what is your name: "
a = gets.chomp
I want to use the first three letters. In this case is for adding other characters and create a different word. How can I separate the string? Can I do the same thing with numbers, with variables that use numbers instead of characters?
This should do the trick:
a[0..2]
numbers that are entered manually are considered string so there should be no problem neither.
Related
I need a regular expression that can be used to find the Nth entry in a comma-separated list.
For example, say this list looks like this:
abc,def,4322,mail#mailinator.com,3321,alpha-beta,43
...and I wanted to find the value of the 7th entry (alpha-beta).
My first thought would not be to use a regular expression, but to use something that splits the string into an array on the comma, but since you asked for a regex.
most regexes allow you to specify a minimum or maximum match, so something like this would probably work.
/(?:[^\,]*,){5}([^,]*)/
This is intended to match any number of character that are not a comma followed by a comma six times exactly (?:[^,]*,){5} - the ?: says to not capture - and then to match and capture any number of characters that are not a comma ([^,]+). You want to use the first capture group.
Let me know if you need more info.
EDIT: I edited the above to not capture the first part of the string. This regex works in C# and Ruby.
You could use something like:
([^,]*,){$m}([^,]*),
As a starting point. (Replace $m with the value of (n-1).) The content would be in capture group 2. This doesn't handle things like lists of size n, but that's just a matter of making the appropriate modifications for your situation.
#list = split /,/ => $string;
$it = $list[6];
or just
$it = (split /,/ => $string)[6];
Beats writing a pattern with a {6} in it every time.
This seems like a simple one, but I am missing something.
I have a number of inputs coming in from a variety of sources and in different formats.
Number inputs
123
123.45
123,45 (note the comma used here to denote decimals)
1,234
1,234.56
12,345.67
12,345,67 (note the comma used here to denote decimals)
Additional info on the inputs
Numbers will always be less than 1 million
EDIT: These are prices, so will either be whole integers or go to the hundredths place
I am trying to write a regex and use gsub to strip out the thousands comma. How do I do this?
I wrote a regex: myregex = /\d+(,)\d{3}/
When I test it in Rubular, it shows that it captures the comma only in the test cases that I want.
But when I run gsub, I get an empty string: inputstr.gsub(myregex,"")
It looks like gsub is capturing everything, not just the comma in (). Where am I going wrong?
result = inputstr.gsub(/,(?=\d{3}\b)/, '')
removes commas only if exactly three digits follow.
(?=...) is a lookahead assertion: It needs to be possible to be matched at the current position, but it's not becoming part of the text that is actually matched (and subsequently replaced).
You are confusing "match" with "capture": to "capture" means to save something so you can refer to it later. You want to capture not the comma, but everything else, and then use the captured portions to build your substitution string.
Try
myregex = /(\d+),(\d{3})/
inputstr.gsub(myregex,'\1\2')
In your example, it is possible to tell from the number of digits after the last separator (either , or .) that it is a decimal point, since there are 2 lone digits. For most cases, if the last group of digits does not have 3 digits then you can assume that the separator in front is decimal point. Another sign is the multiple appearance of a separator in big numbers allows us to differentiate between decimal point and separators.
However, I can give a string 123,456 or 123.456 without any sort of context. It is impossible to tell whether they are "123 thousand 456" or "123 point 456".
You need to scan the document to look for clue whether , is used for thousand separator or decimal point, and vice versa for .. With the context provided, then you can safely apply the same method to remove the thousand separators.
You may also want to check out this article on Wikipedia on the less common ways to specify separators or decimal points. Knowing and deciding not to support is better than assuming things will work.
I am trying to write a program that when a single letter is inputted, if it's in uppercase, leave it in uppercase and return it, and if it's in lowercase, then convert to uppercase. How do I write this to be able to tell if the string is originally in uppercase or lowercase?
Just convert the string to upper case and compare it with the original
string == string.upcase
or for lowercase
string == string.downcase
Edit: as mentioned in the comments the solution above works with English letters only. If you need an international solution instead use
def upcase?(string)
!string[/[[:lower:]]/]
end
which uses a regular expressions to scan the string for lowercase letters and the negates the finding to tell whether the string is all uppercase.
Sounds like you just need to convert to uppercase and don't need to bother with the if lowercase check at all, since applying #upcase to something that is already uppercase won't effect it.
For a single string you can use start_with? method as well.
user_input = gets.chomp
if user_input.start_with?(user_input.downcase)
user_input.upcase!
end
A word processor program features a search and replace function. However, partial words (character combinations found within words) are also replaced. To fix this, I plan to remove extra spaces and use the split function to change the string into an array of words by using " " as a delimiter.
However, once I search through the array, replace the appropriate words, and put the array back into a string separated by spaces, the original formatting of the user will be lost. For example, if the original string was "This is a sentence." and the user wanted "a" to be replaced with "the", the output will be "This is the sentence.", with no additional spaces.
So, my question is whether there is any way to search and replace entire words only while still preserving the formatting (extra spaces) of the user in Visual Basic.
What about using a regex?
In a regex the code \b is a word boundary so for example the regex \ba\b will match a only when a is a whole word.
So for example your code would be:
Dim strPattern As String: strPattern = "\ba\b"
Dim regex As New RegExp
regex.Global = True
regex.Pattern = strPattern
result = regex.Replace("This is a sentence.", "the")
If you use the Split function without removing your extra spaces first your array will have empty items in it so you would not lose the extra spaces and can reconstruct your document with the original formatting in tact.
Why is your formatting lost? If you split the text by space, just attach a space after each element when composing it back from an array. But you will also have to take into account words that end not with a space but punctuation.
in "This is a simple sentence, eh?", "eh" will be stored as "eh?" because u split by space. So you will have to program a complex punctuation-friendly formula or simply use regex. Be prepared - regex is... tricky.
I just want to save the text between two specific points in a string into a variable. The text would look like this:
..."content"=>"The text I want to save to a variable"}]...
I suppose I would have to use scan or slice, but not exactly sure how to pull out just the text without grabbing the RegEx identifiers before and after the text. I tried this, but it didn't work:
var = mystring.slice(/\"content\"\=\>\".\"/)
This should do the job
var = mystring[/"content"=>"(.*)"/, 1]
Note that:
.slice aliases []
none of the characters you escaped are special regexp characters where you're using them
you can "group" the bit you want to keep with ()
.slice / [] take a second parameter to pick a matched group
your_text = '"content"=>"The text I want to save to a variable"'
/"content"=>"(?<hooray>.*)"/ =~ your_text
Afterwards, hooray local variable will be magically set to contain your text. Can be used to set multiple variables.
This regex will match your string:
/\"content\"=>\"(.*)\"/
you can try rubular.com for testing
It looks like you're trying to truncate a sentence. You can split the sentence either on punctuation, or even on words.
mystring.split(".")
mystring.split("word")