Kotlin - How do I concatenate a String to an Int value?

You've got several options:

1. String templates. I think it is the best one. It works absolutely like 2-st solution, but looks better and allow to add some needed characters.

print("$i") 

and if you want to add something

print("$i ") print("$i - is good") 

to add some expression place it in brackets

print("${i + 1} - is better") 

2. toString method which can be used for any object in kotlin.

print(i.toString()) 

3. Java-like solution with concatenating

print("" + i) 

$ dollar – Dollar symbol is used in String templates that we’ll be seeing next

for (i in 15 downTo 10){ print("$i ") } 

Output : 15 14 13 12 11 10

You can use kotlin string template for that:

for (i in 15 downTo 10){ print("$i "); } 

https://kotlinlang.org/docs/reference/basic-types.html#string-templates

The Int::toString method does what you're looking for. Instead of explicit loops, consider functional approaches like map:

(15 downTo 10).map(Int::toString).joinToString { " " } 

Note that the map part is even redundant since joinToString can handle the conversion internally.

The error you get is because the + you're using is the integer one (it is decided by the left operand). The integer + expects 2 integers. In order to actually use the + of String for concatenation, you would need the string on the left, like "" + i + " ".

That being said, it is more idiomatic in Kotlin to print formatted strings using string templates: "$i "

However, if all you want is to print integers with spaces in between, you can use the stdlib function joinToString():

val output = (15 downTo 10).joinToString(" ") print(output) // or println() if you want to start a new line after your integers 

Just cast to String:

for (i in 15 downTo 10){ print(i.toString() + " "); } 

You should use the $ . You can also use the + but it could get confusing in your case because the + has is also an operator which invokes the plus() method which is used to sum Integers.

for (i in 15 downTo 10){ print("$i "); }