I want change "aaa" or "aa..." to "." using Regex(re{2,})
Below is my code
var answer = "aaa"
var re = Regex("re{2,}a") // Regex("are{2,}")
answer = re.replace(answer,".")
println(answer)
Regex("re{2,}a") and Regex("are{2,}")
Both println aaa
How can I replace duplicated string using re{n,} ??
Generic regex to replace any duplicates (not only duplicate a symbols) is (?<symbol>.)\k<symbol>+
You may define an extension function for convenient usage:
private val duplicateRegex = "(?<symbol>.)\\k<symbol>+".toRegex()
fun String.replaceDuplicatesWith(replacement: String): String = replace(duplicateRegex, replacement)
Usage:
println("a".replaceDuplicatesWith(".")) //a
println("aaa".replaceDuplicatesWith(".")) //.
println("aa...".replaceDuplicatesWith(".")) //..
If you want duplicates to be iteratively replaced (like "aa..." -> ".." -> ".") you'll need an auxilary recursive method:
tailrec fun String.iterativelyReplaceDuplicatesWith(replacement: String): String {
val result = this.replaceDuplicatesWith(replacement)
return if (result == this) result else result.iterativelyReplaceDuplicatesWith(replacement)
}
Usage:
println("a".iterativelyReplaceDuplicatesWith(".")) //a
println("aaa".iterativelyReplaceDuplicatesWith(".")) //.
println("aa...".iterativelyReplaceDuplicatesWith(".")) //.
fun main(args: Array<String>) {
var tests = arrayOf("a","aa","aaa","aaaa")
val re = Regex("a(a+)")
tests.forEach {t->
val result = re.replace(t,".")
println(result)
}
}
output:
a . . .
aa...is just a notation for bunch ofacharacters?