toCharArray  
  inline fun String.toCharArray(destination: CharArray, destinationOffset: Int = 0, startIndex: Int = 0, endIndex: Int = length): CharArray(source)
Copies characters from this string into the destination character array and returns that array.
Since Kotlin
1.0Parameters
destination
the array to copy to.
destinationOffset 
the position in the array to copy to.
startIndex 
the start offset (inclusive) of the substring to copy.
endIndex 
the end offset (exclusive) of the substring to copy.
Returns a CharArray containing characters of this string.