Hi all another what are the expectations here question based

Question

Hi all another what are the expectations here question based on a question in the JetBrains hyperskill Kotlin course I have a question that asks what are the expected inputs for the following snippet of code ```val scanner = Scanner System `in` val s1 = scanner nextLine val s2 = scanner nextLine val num = scanner nextInt ``` The answers are roughly a ```ABC DEF 123``` b ```ABC DEF 123``` c ```10 ABC 3``` d ```ABC DEF 123``` Looking the behavior in kotlin file locally the only answer that doesn t throw an error is `a` but not according to the course page Is this a Kotlin version issue A JVM issue Apparently the correct answer is `c` but the first Int is confusing me Any hints or clarity would be most appreciated Thank you

Joffrey · Answer

`readLine ` can read any text it doesn t have to be letters Since we don t see the rest of the program it could really be anything

CanOfBees · Answer

< Joffrey> thanks for the response That makes sense looking at the docs for `readLine ` but `nextLine ` only seems to applicable to strings

Joffrey · Answer

My bad I meant `nextLine` Strings can be anything including numbers

phldavies · Answer

` 10 ` is still a string wink

CanOfBees · Answer

< phldavies> thank you I m surprised I was certain that there was a difference between `10` and ` 10 ` first is an Int and the second is a String but that s wrong `10` is a string unless it is explicitly typed

Vampire · Answer

But how would A work The only sensible answer is C `nextLine` reads a line `nextInt` reads an int so it has to be three lines and the only option with that is C

Vampire · Answer

Regarding `10` vs ` 10 ` coming as input the first is a two character string the latter is a four character string The quotes are just significant when writing a string literal in source code

CanOfBees · Answer

< Vampire> hi there As I mentioned I suppose I was confused by two things Firstly C looks like int string int and secondly `nextLine` talks about strings Glad to learn that quotes are only significant in literals in source code not in input for the `scanner` example

phldavies · Answer

We re talking here about reading from an input stream using a `Scanner` in this case the input stream is the following ```10 n ABC n 3``` I ve added ` n` to highlight the line endings `Scanner nextLine ` is reading the characters if the input stream until the next ` n` and returning the string value In this case it s returning the `String` of ` 10 ` this is still nothing to do with the Kotlin representation of string vs integer in the code The two calls to `nextLine ` each advance the scanner to after the ` n` Starting with ```|10 n ABC n 3``` then after one call to `nextLine ` ``` 10 n |ABC n 3``` and finally after the second call to `nextLine ` ``` 10 n ABC n 3``` Then the call to `nextInt ` reads the next token by default delimited by whitespace and then interprets this value as an integer

CanOfBees · Answer

< phldavies> yes I m almost there I m probably too focused on types at this point I appreciate your and < Vampire> s clarifications

CanOfBees · Answer

I apologize if I seem like I m belaboring this I m wondering what to expect when I run this locally ```import java util Scanner fun main println hello let s go explore val scanner = Scanner System `in` val s1 = scanner nextLine val s2 = scanner nextLine val num = scanner nextInt println s1 println s2 println num ``` I m running this in IntelliJ 2022 1 1 with OpenJDK 11 and Kotlin 221 1 6 21 release I can enter ```10 n abc n``` and then an error is thrown ```Exception in thread main java util InputMismatchException at java base java util Scanner throwFor Scanner java 939 at java base java util Scanner next Scanner java 1594 at java base java util Scanner nextInt Scanner java 2258 at java base java util Scanner nextInt Scanner java 2212 at ExploreKt main explore kt 9 at ExploreKt main explore kt ```

Youssef Shoaib [MOD] · Answer

Basically if you re reading from a Scanner or any form of input stream you re taking in bytes of information Usually and especially in the case of `<http System in|System in>` those bytes are interpreted as Strings So when you call `nextInt` the Scanner interprets the bytes as a string first checks that they re a valid int and if that string parses to a valid int it is simply returned to you

Youssef Shoaib [MOD] · Answer

In other words `nextInt` is similar to `next` followed by a `Integer parseInt` and so every integer you read from a console file or any other ASCII formatted thing will be first and foremost a valid string before it is an int

Vampire · Answer

That s overly simplified though as it also does things like removing group separators locale specific prefixes and so on