kotlin-stdlib / kotlin.io / java.io.File / toRelativeString toRelativeString fun File.toRelativeString(base: File): String (source) Platform and version requirements: JVM Calculates the relative path for this file from base file. Note that the base file is treated as a directory. If this file matches the base file, then an empty string will be returned. Exceptions IllegalArgumentException - if this and base paths have different roots. Return relative path from base to this.