\u escape, in regular expressions, 469
UDP (User Datagram Protocol), 292–293
UdpClient class, 293
UI culture, 312–313
UI, permission to access, 338
UI threads, 387
uint16 type, IL, 172
uint32 type, IL, 172
uint64 type, IL, 172
UIPermission class, 338
unaligned. prefix, IL, 575
unbox instruction, IL, 93, 568
unboxing
of collections, 73–74
definition of, 23
of values, 93
undeniable exceptions, 109–110
underflow, floating points, 183
unhandled exceptions
in constructors, 42–43
definition of, 99, 108–109
Unicode character encoding
books about, 493
definition of, 302
Unicode properties, in regular expressions, 472–473
unification of objects and values, 22–24
Uniform Resource Locator (URL), 293
UnionCodeGroup class, 334
unmanaged code, 403. See also interoperability; managed code
UnManagedMemoryStream class, 280
unsignaled mutexes, 372
unsigned int8 type, IL, 17, 172
unsigned int16 type, IL, 17
unsigned int32 type, IL, 17
unsigned int64 type, IL, 17
unsigned native int type, IL, 18, 405
Unstarted state, Thread object, 358, 359
untrusted code, CAS, 332
URL (Uniform Resource Locator), 293
UrlIdentityPermission class, 340
User Datagram Protocol (UDP), 292–293
User policy level, 341
user-based security
access controls, 348–351
impersonation, 348
simple authentication, 347–348
user identity for, 347–348
using keyword, C#, 59
UTF-7 encoding, 320
UTF-8 encoding, 320