Type inference is one of the most powerful features in Kotlin, but sometimes it becomes hazardous when the type of variable is unknown. For example, we are asked to write a function that can take variable of the Any type. This can be float, string, or int:

fun func(x: Any) { 
    // What is the type of x  
}

To handle this tricky situation, Kotlin provides an is keyword to verify the variable type. The syntax for this is as follows:

x is Int
x is Char

This check will return true if x is an integer or character; otherwise, it will return false. Check the following examples:

fun func(x: Any) { 
  if(x is Float){
     println("x is Float")
  } else if(x is String){
     println("x is String")
}

!is can be used to verify whether or not a variable is a required type:

fun func(x: Any) { 
  if(x !is Float){
     println("f is not Float")
  }
}