Platform and version requirements: JVM (1.0), JS (1.0), Native (1.0)

fun CharSequence.singleOrNull(): Char?

Returns single character, or null if the char sequence is empty or has more than one character.

Platform and version requirements: JVM (1.0), JS (1.0), Native (1.0)

inline fun CharSequence.singleOrNull(
    predicate: (Char) -> Boolean
): Char?

Returns the single character matching the given predicate, or null if character was not found or more than one character was found.