RtlCharToInteger - NtDoc

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

NTSYSAPI
NTSTATUS
NTAPI
RtlCharToInteger(
    _In_ PCSTR String,
    _In_opt_ ULONG Base,
    _Out_ PULONG Value
    );

#endif

View code on GitHub

This function is documented in Windows Driver Kit.