So i have a string text = "" and when i want to increment i use text+= "something", but i need to make a break line because i will write that text a couple times repeated, but when i do text+="\n" it adds the spaces between the "something" texts but after that it adds another space that i dont want.
I would not do it iteratively. So instead of using a loop, you can use joinToString for that, like this:
lines.joinToString(separator = "\n")
val result = string.substringBeforeLast("\n")
This might help!
fun main() {
var string=""
for (line in 0 until 4){
string += "Something"
if (line!=3){
string+="\n"
}
}
print(string)
}
Related
I have declared 2 variables to read from console but on other case i want to read just one of them but i can't.
My code:
print("Enter two numbers in format: {source base} {target base} (To quit type /exit) ")
val (sourceBase, targetBase) = readLine()!!.split(" ")
`I can't type /exit because i've got IndexOutOfBoundsException.
Any tips?
Edit: Thank you all for respond, especially lukas.j, it's working now.
Add a second element, an empty string, if the splitted readLine() contains less than 2 elements:
val (sourceBase, targetBase) = readLine()!!.split(" ").let { if (it.size < 2) it + "" else it }
example:
a variable
val str = readln().replace("[^A-Za-z0-9 ] \\s+".toRegex(),"").trim()
should read multiple lines of input value, input value will be like this
heading
----------
topic1
topic2
or like this
heading
-------
a) topic1
b) topic2
input may contain special characters or tabs or spaces we need to remove them also
I don't know what your Regex is trying to do, but that's not really your question.
How do you know when the user has finished their input - a special word or an empty line?
Assuming an empty line, here's how you can get all the content
println("Enter something:")
var lines = ""
do {
val line = readLine()
lines += "${clean(line)}\n"
} while (!line.isNullOrBlank())
println("User input:\n$lines")
private fun clean(line: String?): String? {
return line?.replace("[^A-Za-z0-9 ] \\s+".toRegex(),"")?.trim()
}
I am trying to replace a few sub strings inside a string. But my code doesn't seem to work.
val listOfMaleWords = listOf(" him", " he", " his")
val listOfFemaleWords = listOf(" her", " she", " her")
fun modifyIdeaForGender(rawIdea : String, desiredGender : String): String {
var theRawIdea = rawIdea
if (desiredGender == "FEMALE") {
println("desired gender is FEMALE")
listOfMaleWords.forEachIndexed { index, element ->
theRawIdea.replace(element, listOfFemaleWords[index])
}
} else {
println("desired gender is MALE")
listOfFemaleWords.forEachIndexed { index, element ->
theRawIdea.replace(element, listOfMaleWords[index])
}
}
return theRawIdea
}
fun main() {
var sampleString : String = "Tell him, he is special"
println(modifyIdeaForGender(sampleString, "FEMALE"))
}
Expected Output :
"Tell her, she is special"
Current Output :
"Tell him, he is special" // no change
Whats wrong with my code? The current output doesn't replace the string characters at all.
replace returns a new String that you are discarding immediately. It does not mutate theRawIdea itself, so you should assign it back to theRawIdea yourself. For example:
theRawIdea = theRawIdea.replace(element, listOfFemaleWords[index])
Though this would modify theRawIdea as you desire, it wouldn't replace the pronouns correctly. Once it replaces the "him"s with "her"s, it would try to replace the "he"s with "she"s. But note that "he" a substring of "her"! So this would produce:
Tell sher, she is special
This could be fixed by reordering the lists, putting the "he"-"she" pair first, or by using regex, adding \b word boundary anchors around the words:
// note that you should not have spaces before the words if you decide to use \b
val listOfMaleWords = listOf("him", "he", "his")
val listOfFemaleWords = listOf("her", "she", "her")
...
theRawIdea = theRawIdea.replace("\\b$element\\b".toRegex(), listOfFemaleWords[index])
Note that this doesn't account for capitalisation or the fact that changing from female gender pronouns to male ones is inherently broken. Your current code would change all her to him. It would require some more complicated natural language processing to accurately do this task in general.
Taking all that into account, I've rewritten your code with zip:
fun modifyMaleIdeaToFemaleGender(rawIdea : String): String {
var theRawIdea = rawIdea
// if you really want to do the broken female to male case, then this would be
// listOfFemaleWords zip listOfMaleWords
// and the loop below can stay the same
val zipped = listOfMaleWords zip listOfFemaleWords
zipped.forEach { (target, replacement) ->
theRawIdea = theRawIdea.replace("\\b$target\\b".toRegex(), replacement)
}
return theRawIdea
}
You can also use fold to avoid reassigning theRawIdea:
fun modifyIdeaToFemaleGender(rawIdea : String): String {
val zipped = listOfMaleWords zip listOfFemaleWords
return zipped.fold(rawIdea) { acc, (target, replacement) ->
acc.replace("\\b$target\\b".toRegex(), replacement)
}
}
Your code assumes that the replace() method performs an in-place mutation of the string. However, the string with the replaced values are returned by the replace(). So you need to change your code to contain something like:
theRawIdea = theRawIdea.replace(element, listOfFemaleWords[index])
To do this, you will have to use a conventional loop instead of listOfMaleWords.forEachIndexed style looping.
I rather have this ugly way of building a string from a list as:
val input = listOf("[A,B]", "[C,D]")
val builder = StringBuilder()
builder.append("Serialized('IDs((")
for (pt in input) {
builder.append(pt[0] + " " + pt[1])
builder.append(", ")
}
builder.append("))')")
The problem is that it adds a comma after the last element and if I want to avoid that I need to add another if check in the loop for the last element.
I wonder if there is a more concise way of doing this in kotlin?
EDIT
End result should be something like:
Serialized('IDs((A B,C D))')
In Kotlin you can use joinToString for this kind of use case (it deals with inserting the separator only between elements).
It is very versatile because it allows to specify a transform function for each element (in addition to the more classic separator, prefix, postfix). This makes it equivalent to mapping all elements to strings and then joining them together, but in one single call.
If input really is a List<List<String>> like you mention in the title and you assume in your loop, you can use:
input.joinToString(
prefix = "Serialized('IDs((",
postfix = "))')",
separator = ", ",
) { (x, y) -> "$x $y" }
Note that the syntax with (x, y) is a destructuring syntax that automatically gets the first and second element of the lists inside your list (parentheses are important).
If your input is in fact a List<String> as in listOf("[A,B]", "[C,D]") that you wrote at the top of your code, you can instead use:
input.joinToString(
prefix = "Serialized('IDs((",
postfix = "))')",
separator = ", ",
) { it.removeSurrounding("[", "]").replace(",", " ") }
val input = listOf("[A,B]", "[C,D]")
val result =
"Serialized('IDs((" +
input.joinToString(",") { it.removeSurrounding("[", "]").replace(",", " ") } +
"))')"
println(result) // Output: Serialized('IDs((A B,C D))')
Kotlin provides an extension function [joinToString][1] (in Iterable) for this type of purpose.
input.joinToString(",", "Serialized('IDs((", "))')")
This will correctly add the separator.
i'm trying to get multiple input from user and i'm using readlint()!! following by for loop when i go try to print those input back it only shows one output which is the last one...
And i have tried .split(' ') method which is kinda better than for Loop trick but i want my program more better..
1- it take input from new line(for Multiple inputs)
2- it print out all user input
here's my code and it prints out in one line
fun getTheData() {
try{
val(a,b,c) = readLine()!!.split(' ')
println("$a , $b, $c")
}catch (ex: IndexOutOfBoundsException){
println("invalid")
}
}
Here you're only reading one line.
The split() function simply splits your single line into multiple parts separated by a single whitespace.
In short, if you input 1 2 3 in one line, it will print the 3 numbers. However, if you input several lines, you'll only get the first line, as you never read other lines (only one call to readLine()).
In order to read more lines, you do need some sort of loop, like:
fun main() {
while(true) {
val line = readLine()!!
println(line)
}
}