/*
A small program that demonstrates how to extract all digits
from a string using Kotlin's expressive standard library.
The approach:
- Use a dedicated function for clarity
- Iterate through characters using Kotlin's built‑in tools
- Filter only digit characters
- Build the result efficiently
*/
fun extractDigits(s: String): String {
/*
Walk through each character and keep only those
recognized as digits. Kotlin's Char.isDigit()
is Unicode‑aware and efficient.
*/
return s.filter { it.isDigit() }
}
fun main() {
// Example input string
val str = "5 rustc#8go 9001 c c++ 17python"
// Extract digits
val digits = extractDigits(str)
// Display results
println("Original: $str")
println("Digits: $digits")
}
/*
run:
Original: 5 rustc#8go 9001 c c++ 17python
Digits: 58900117
*/
