Can you explain the concept of inline functions in Kotlin and their advantages?

In Kotlin, the keyword inline is used for functions so that the compiler, during compilation, inserts the body of the function directly into the call sites instead of a normal call by reference. This is especially useful for higher-order functions that accept lambda expressions.

Advantages of inline functions:

• Reducing call overhead. When using lambdas without inline, objects are created and additional calls are made, which reduces performance.
• Improving performance. Direct code insertion allows avoiding the creation of additional objects and calls.
• The ability to use noinline and crossinline. Allows flexible management of lambda behavior inside inline functions.

Example:

inline fun measureTime(block: () -> Unit) {
    val start = System.currentTimeMillis()
    block()
    val end = System.currentTimeMillis()
    println("Execution time: ${end - start} ms")
}

fun main() {
    measureTime {
        // some code
        Thread.sleep(100)
    }
}

Here, measureTime is an inline function, and the lambda body will be inserted directly, reducing overhead.