RtlIpv4AddressToStringW - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTRTL_H

NTSYSAPI
PWSTR
NTAPI
RtlIpv4AddressToStringW(
    _In_ PCIN_ADDR Address,
    _Out_writes_(16) PWSTR AddressString
    );

#endif

View code on GitHub

This function is documented in Windows SDK.