Can you explain what it means to use an inline function in Kotlin and how it differs from a regular function?

In Kotlin, the keyword inline is used for functions to have the compiler insert the function body directly at the call site, instead of the usual call through the stack. This reduces the overhead of function calls, especially useful for higher-order functions that accept lambda expressions.

Differences from a regular function:

• Performance: inline functions can improve performance by eliminating the function call.
• Lambda expressions: when using inline functions, lambdas do not create additional objects, reducing garbage collection load.

Example:

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

fun main() {
    measureTime {
        println("Code is executing")
    }
}

Here, measureTime is an inline function, and its body will be inserted into main instead of a regular call.