ext_ffi_api.html (21471B)
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 2 <html> 3 <head> 4 <title>ffi.* API Functions</title> 5 <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> 6 <meta name="Author" content="Mike Pall"> 7 <meta name="Copyright" content="Copyright (C) 2005-2016, Mike Pall"> 8 <meta name="Language" content="en"> 9 <link rel="stylesheet" type="text/css" href="bluequad.css" media="screen"> 10 <link rel="stylesheet" type="text/css" href="bluequad-print.css" media="print"> 11 <style type="text/css"> 12 table.abitable { width: 30em; line-height: 1.2; } 13 tr.abihead td { font-weight: bold; } 14 td.abiparam { font-weight: bold; width: 6em; } 15 </style> 16 </head> 17 <body> 18 <div id="site"> 19 <a href="http://luajit.org"><span>Lua<span id="logo">JIT</span></span></a> 20 </div> 21 <div id="head"> 22 <h1><tt>ffi.*</tt> API Functions</h1> 23 </div> 24 <div id="nav"> 25 <ul><li> 26 <a href="luajit.html">LuaJIT</a> 27 <ul><li> 28 <a href="http://luajit.org/download.html">Download <span class="ext">»</span></a> 29 </li><li> 30 <a href="install.html">Installation</a> 31 </li><li> 32 <a href="running.html">Running</a> 33 </li></ul> 34 </li><li> 35 <a href="extensions.html">Extensions</a> 36 <ul><li> 37 <a href="ext_ffi.html">FFI Library</a> 38 <ul><li> 39 <a href="ext_ffi_tutorial.html">FFI Tutorial</a> 40 </li><li> 41 <a class="current" href="ext_ffi_api.html">ffi.* API</a> 42 </li><li> 43 <a href="ext_ffi_semantics.html">FFI Semantics</a> 44 </li></ul> 45 </li><li> 46 <a href="ext_jit.html">jit.* Library</a> 47 </li><li> 48 <a href="ext_c_api.html">Lua/C API</a> 49 </li><li> 50 <a href="ext_profiler.html">Profiler</a> 51 </li></ul> 52 </li><li> 53 <a href="status.html">Status</a> 54 <ul><li> 55 <a href="changes.html">Changes</a> 56 </li></ul> 57 </li><li> 58 <a href="faq.html">FAQ</a> 59 </li><li> 60 <a href="http://luajit.org/performance.html">Performance <span class="ext">»</span></a> 61 </li><li> 62 <a href="http://wiki.luajit.org/">Wiki <span class="ext">»</span></a> 63 </li><li> 64 <a href="http://luajit.org/list.html">Mailing List <span class="ext">»</span></a> 65 </li></ul> 66 </div> 67 <div id="main"> 68 <p> 69 This page describes the API functions provided by the FFI library in 70 detail. It's recommended to read through the 71 <a href="ext_ffi.html">introduction</a> and the 72 <a href="ext_ffi_tutorial.html">FFI tutorial</a> first. 73 </p> 74 75 <h2 id="glossary">Glossary</h2> 76 <ul> 77 <li><b>cdecl</b> — An abstract C type declaration (a Lua 78 string).</li> 79 <li><b>ctype</b> — A C type object. This is a special kind of 80 <b>cdata</b> returned by <tt>ffi.typeof()</tt>. It serves as a 81 <b>cdata</b> <a href="#ffi_new">constructor</a> when called.</li> 82 <li><b>cdata</b> — A C data object. It holds a value of the 83 corresponding <b>ctype</b>.</li> 84 <li><b>ct</b> — A C type specification which can be used for 85 most of the API functions. Either a <b>cdecl</b>, a <b>ctype</b> or a 86 <b>cdata</b> serving as a template type.</li> 87 <li><b>cb</b> — A callback object. This is a C data object 88 holding a special function pointer. Calling this function from 89 C code runs an associated Lua function.</li> 90 <li><b>VLA</b> — A variable-length array is declared with a 91 <tt>?</tt> instead of the number of elements, e.g. <tt>"int[?]"</tt>. 92 The number of elements (<tt>nelem</tt>) must be given when it's 93 <a href="#ffi_new">created</a>.</li> 94 <li><b>VLS</b> — A variable-length struct is a <tt>struct</tt> C 95 type where the last element is a <b>VLA</b>. The same rules for 96 declaration and creation apply.</li> 97 </ul> 98 99 <h2 id="decl">Declaring and Accessing External Symbols</h2> 100 <p> 101 External symbols must be declared first and can then be accessed by 102 indexing a <a href="ext_ffi_semantics.html#clib">C library 103 namespace</a>, which automatically binds the symbol to a specific 104 library. 105 </p> 106 107 <h3 id="ffi_cdef"><tt>ffi.cdef(def)</tt></h3> 108 <p> 109 Adds multiple C declarations for types or external symbols (named 110 variables or functions). <tt>def</tt> must be a Lua string. It's 111 recommended to use the syntactic sugar for string arguments as 112 follows: 113 </p> 114 <pre class="code"> 115 ffi.cdef[[ 116 <span style="color:#00a000;">typedef struct foo { int a, b; } foo_t; // Declare a struct and typedef. 117 int dofoo(foo_t *f, int n); /* Declare an external C function. */</span> 118 ]] 119 </pre> 120 <p> 121 The contents of the string (the part in green above) must be a 122 sequence of 123 <a href="ext_ffi_semantics.html#clang">C declarations</a>, 124 separated by semicolons. The trailing semicolon for a single 125 declaration may be omitted. 126 </p> 127 <p> 128 Please note that external symbols are only <em>declared</em>, but they 129 are <em>not bound</em> to any specific address, yet. Binding is 130 achieved with C library namespaces (see below). 131 </p> 132 <p style="color: #c00000;"> 133 C declarations are not passed through a C pre-processor, 134 yet. No pre-processor tokens are allowed, except for 135 <tt>#pragma pack</tt>. Replace <tt>#define</tt> in existing 136 C header files with <tt>enum</tt>, <tt>static const</tt> 137 or <tt>typedef</tt> and/or pass the files through an external 138 C pre-processor (once). Be careful not to include unneeded or 139 redundant declarations from unrelated header files. 140 </p> 141 142 <h3 id="ffi_C"><tt>ffi.C</tt></h3> 143 <p> 144 This is the default C library namespace — note the 145 uppercase <tt>'C'</tt>. It binds to the default set of symbols or 146 libraries on the target system. These are more or less the same as a 147 C compiler would offer by default, without specifying extra link 148 libraries. 149 </p> 150 <p> 151 On POSIX systems, this binds to symbols in the default or global 152 namespace. This includes all exported symbols from the executable and 153 any libraries loaded into the global namespace. This includes at least 154 <tt>libc</tt>, <tt>libm</tt>, <tt>libdl</tt> (on Linux), 155 <tt>libgcc</tt> (if compiled with GCC), as well as any exported 156 symbols from the Lua/C API provided by LuaJIT itself. 157 </p> 158 <p> 159 On Windows systems, this binds to symbols exported from the 160 <tt>*.exe</tt>, the <tt>lua51.dll</tt> (i.e. the Lua/C API 161 provided by LuaJIT itself), the C runtime library LuaJIT was linked 162 with (<tt>msvcrt*.dll</tt>), <tt>kernel32.dll</tt>, 163 <tt>user32.dll</tt> and <tt>gdi32.dll</tt>. 164 </p> 165 166 <h3 id="ffi_load"><tt>clib = ffi.load(name [,global])</tt></h3> 167 <p> 168 This loads the dynamic library given by <tt>name</tt> and returns 169 a new C library namespace which binds to its symbols. On POSIX 170 systems, if <tt>global</tt> is <tt>true</tt>, the library symbols are 171 loaded into the global namespace, too. 172 </p> 173 <p> 174 If <tt>name</tt> is a path, the library is loaded from this path. 175 Otherwise <tt>name</tt> is canonicalized in a system-dependent way and 176 searched in the default search path for dynamic libraries: 177 </p> 178 <p> 179 On POSIX systems, if the name contains no dot, the extension 180 <tt>.so</tt> is appended. Also, the <tt>lib</tt> prefix is prepended 181 if necessary. So <tt>ffi.load("z")</tt> looks for <tt>"libz.so"</tt> 182 in the default shared library search path. 183 </p> 184 <p> 185 On Windows systems, if the name contains no dot, the extension 186 <tt>.dll</tt> is appended. So <tt>ffi.load("ws2_32")</tt> looks for 187 <tt>"ws2_32.dll"</tt> in the default DLL search path. 188 </p> 189 190 <h2 id="create">Creating cdata Objects</h2> 191 <p> 192 The following API functions create cdata objects (<tt>type()</tt> 193 returns <tt>"cdata"</tt>). All created cdata objects are 194 <a href="ext_ffi_semantics.html#gc">garbage collected</a>. 195 </p> 196 197 <h3 id="ffi_new"><tt>cdata = ffi.new(ct [,nelem] [,init...])<br> 198 cdata = <em>ctype</em>([nelem,] [init...])</tt></h3> 199 <p> 200 Creates a cdata object for the given <tt>ct</tt>. VLA/VLS types 201 require the <tt>nelem</tt> argument. The second syntax uses a ctype as 202 a constructor and is otherwise fully equivalent. 203 </p> 204 <p> 205 The cdata object is initialized according to the 206 <a href="ext_ffi_semantics.html#init">rules for initializers</a>, 207 using the optional <tt>init</tt> arguments. Excess initializers cause 208 an error. 209 </p> 210 <p> 211 Performance notice: if you want to create many objects of one kind, 212 parse the cdecl only once and get its ctype with 213 <tt>ffi.typeof()</tt>. Then use the ctype as a constructor repeatedly. 214 </p> 215 <p style="font-size: 8pt;"> 216 Please note that an anonymous <tt>struct</tt> declaration implicitly 217 creates a new and distinguished ctype every time you use it for 218 <tt>ffi.new()</tt>. This is probably <b>not</b> what you want, 219 especially if you create more than one cdata object. Different anonymous 220 <tt>structs</tt> are not considered assignment-compatible by the 221 C standard, even though they may have the same fields! Also, they 222 are considered different types by the JIT-compiler, which may cause an 223 excessive number of traces. It's strongly suggested to either declare 224 a named <tt>struct</tt> or <tt>typedef</tt> with <tt>ffi.cdef()</tt> 225 or to create a single ctype object for an anonymous <tt>struct</tt> 226 with <tt>ffi.typeof()</tt>. 227 </p> 228 229 <h3 id="ffi_typeof"><tt>ctype = ffi.typeof(ct)</tt></h3> 230 <p> 231 Creates a ctype object for the given <tt>ct</tt>. 232 </p> 233 <p> 234 This function is especially useful to parse a cdecl only once and then 235 use the resulting ctype object as a <a href="#ffi_new">constructor</a>. 236 </p> 237 238 <h3 id="ffi_cast"><tt>cdata = ffi.cast(ct, init)</tt></h3> 239 <p> 240 Creates a scalar cdata object for the given <tt>ct</tt>. The cdata 241 object is initialized with <tt>init</tt> using the "cast" variant of 242 the <a href="ext_ffi_semantics.html#convert">C type conversion 243 rules</a>. 244 </p> 245 <p> 246 This functions is mainly useful to override the pointer compatibility 247 checks or to convert pointers to addresses or vice versa. 248 </p> 249 250 <h3 id="ffi_metatype"><tt>ctype = ffi.metatype(ct, metatable)</tt></h3> 251 <p> 252 Creates a ctype object for the given <tt>ct</tt> and associates it with 253 a metatable. Only <tt>struct</tt>/<tt>union</tt> types, complex numbers 254 and vectors are allowed. Other types may be wrapped in a 255 <tt>struct</tt>, if needed. 256 </p> 257 <p> 258 The association with a metatable is permanent and cannot be changed 259 afterwards. Neither the contents of the <tt>metatable</tt> nor the 260 contents of an <tt>__index</tt> table (if any) may be modified 261 afterwards. The associated metatable automatically applies to all uses 262 of this type, no matter how the objects are created or where they 263 originate from. Note that pre-defined operations on types have 264 precedence (e.g. declared field names cannot be overriden). 265 </p> 266 <p> 267 All standard Lua metamethods are implemented. These are called directly, 268 without shortcuts and on any mix of types. For binary operations, the 269 left operand is checked first for a valid ctype metamethod. The 270 <tt>__gc</tt> metamethod only applies to <tt>struct</tt>/<tt>union</tt> 271 types and performs an implicit <a href="#ffi_gc"><tt>ffi.gc()</tt></a> 272 call during creation of an instance. 273 </p> 274 275 <h3 id="ffi_gc"><tt>cdata = ffi.gc(cdata, finalizer)</tt></h3> 276 <p> 277 Associates a finalizer with a pointer or aggregate cdata object. The 278 cdata object is returned unchanged. 279 </p> 280 <p> 281 This function allows safe integration of unmanaged resources into the 282 automatic memory management of the LuaJIT garbage collector. Typical 283 usage: 284 </p> 285 <pre class="code"> 286 local p = ffi.gc(ffi.C.malloc(n), ffi.C.free) 287 ... 288 p = nil -- Last reference to p is gone. 289 -- GC will eventually run finalizer: ffi.C.free(p) 290 </pre> 291 <p> 292 A cdata finalizer works like the <tt>__gc</tt> metamethod for userdata 293 objects: when the last reference to a cdata object is gone, the 294 associated finalizer is called with the cdata object as an argument. The 295 finalizer can be a Lua function or a cdata function or cdata function 296 pointer. An existing finalizer can be removed by setting a <tt>nil</tt> 297 finalizer, e.g. right before explicitly deleting a resource: 298 </p> 299 <pre class="code"> 300 ffi.C.free(ffi.gc(p, nil)) -- Manually free the memory. 301 </pre> 302 303 <h2 id="info">C Type Information</h2> 304 <p> 305 The following API functions return information about C types. 306 They are most useful for inspecting cdata objects. 307 </p> 308 309 <h3 id="ffi_sizeof"><tt>size = ffi.sizeof(ct [,nelem])</tt></h3> 310 <p> 311 Returns the size of <tt>ct</tt> in bytes. Returns <tt>nil</tt> if 312 the size is not known (e.g. for <tt>"void"</tt> or function types). 313 Requires <tt>nelem</tt> for VLA/VLS types, except for cdata objects. 314 </p> 315 316 <h3 id="ffi_alignof"><tt>align = ffi.alignof(ct)</tt></h3> 317 <p> 318 Returns the minimum required alignment for <tt>ct</tt> in bytes. 319 </p> 320 321 <h3 id="ffi_offsetof"><tt>ofs [,bpos,bsize] = ffi.offsetof(ct, field)</tt></h3> 322 <p> 323 Returns the offset (in bytes) of <tt>field</tt> relative to the start 324 of <tt>ct</tt>, which must be a <tt>struct</tt>. Additionally returns 325 the position and the field size (in bits) for bit fields. 326 </p> 327 328 <h3 id="ffi_istype"><tt>status = ffi.istype(ct, obj)</tt></h3> 329 <p> 330 Returns <tt>true</tt> if <tt>obj</tt> has the C type given by 331 <tt>ct</tt>. Returns <tt>false</tt> otherwise. 332 </p> 333 <p> 334 C type qualifiers (<tt>const</tt> etc.) are ignored. Pointers are 335 checked with the standard pointer compatibility rules, but without any 336 special treatment for <tt>void *</tt>. If <tt>ct</tt> specifies a 337 <tt>struct</tt>/<tt>union</tt>, then a pointer to this type is accepted, 338 too. Otherwise the types must match exactly. 339 </p> 340 <p> 341 Note: this function accepts all kinds of Lua objects for the 342 <tt>obj</tt> argument, but always returns <tt>false</tt> for non-cdata 343 objects. 344 </p> 345 346 <h2 id="util">Utility Functions</h2> 347 348 <h3 id="ffi_errno"><tt>err = ffi.errno([newerr])</tt></h3> 349 <p> 350 Returns the error number set by the last C function call which 351 indicated an error condition. If the optional <tt>newerr</tt> argument 352 is present, the error number is set to the new value and the previous 353 value is returned. 354 </p> 355 <p> 356 This function offers a portable and OS-independent way to get and set the 357 error number. Note that only <em>some</em> C functions set the error 358 number. And it's only significant if the function actually indicated an 359 error condition (e.g. with a return value of <tt>-1</tt> or 360 <tt>NULL</tt>). Otherwise, it may or may not contain any previously set 361 value. 362 </p> 363 <p> 364 You're advised to call this function only when needed and as close as 365 possible after the return of the related C function. The 366 <tt>errno</tt> value is preserved across hooks, memory allocations, 367 invocations of the JIT compiler and other internal VM activity. The same 368 applies to the value returned by <tt>GetLastError()</tt> on Windows, but 369 you need to declare and call it yourself. 370 </p> 371 372 <h3 id="ffi_string"><tt>str = ffi.string(ptr [,len])</tt></h3> 373 <p> 374 Creates an interned Lua string from the data pointed to by 375 <tt>ptr</tt>. 376 </p> 377 <p> 378 If the optional argument <tt>len</tt> is missing, <tt>ptr</tt> is 379 converted to a <tt>"char *"</tt> and the data is assumed to be 380 zero-terminated. The length of the string is computed with 381 <tt>strlen()</tt>. 382 </p> 383 <p> 384 Otherwise <tt>ptr</tt> is converted to a <tt>"void *"</tt> and 385 <tt>len</tt> gives the length of the data. The data may contain 386 embedded zeros and need not be byte-oriented (though this may cause 387 endianess issues). 388 </p> 389 <p> 390 This function is mainly useful to convert (temporary) 391 <tt>"const char *"</tt> pointers returned by 392 C functions to Lua strings and store them or pass them to other 393 functions expecting a Lua string. The Lua string is an (interned) copy 394 of the data and bears no relation to the original data area anymore. 395 Lua strings are 8 bit clean and may be used to hold arbitrary, 396 non-character data. 397 </p> 398 <p> 399 Performance notice: it's faster to pass the length of the string, if 400 it's known. E.g. when the length is returned by a C call like 401 <tt>sprintf()</tt>. 402 </p> 403 404 <h3 id="ffi_copy"><tt>ffi.copy(dst, src, len)<br> 405 ffi.copy(dst, str)</tt></h3> 406 <p> 407 Copies the data pointed to by <tt>src</tt> to <tt>dst</tt>. 408 <tt>dst</tt> is converted to a <tt>"void *"</tt> and <tt>src</tt> 409 is converted to a <tt>"const void *"</tt>. 410 </p> 411 <p> 412 In the first syntax, <tt>len</tt> gives the number of bytes to copy. 413 Caveat: if <tt>src</tt> is a Lua string, then <tt>len</tt> must not 414 exceed <tt>#src+1</tt>. 415 </p> 416 <p> 417 In the second syntax, the source of the copy must be a Lua string. All 418 bytes of the string <em>plus a zero-terminator</em> are copied to 419 <tt>dst</tt> (i.e. <tt>#src+1</tt> bytes). 420 </p> 421 <p> 422 Performance notice: <tt>ffi.copy()</tt> may be used as a faster 423 (inlinable) replacement for the C library functions 424 <tt>memcpy()</tt>, <tt>strcpy()</tt> and <tt>strncpy()</tt>. 425 </p> 426 427 <h3 id="ffi_fill"><tt>ffi.fill(dst, len [,c])</tt></h3> 428 <p> 429 Fills the data pointed to by <tt>dst</tt> with <tt>len</tt> constant 430 bytes, given by <tt>c</tt>. If <tt>c</tt> is omitted, the data is 431 zero-filled. 432 </p> 433 <p> 434 Performance notice: <tt>ffi.fill()</tt> may be used as a faster 435 (inlinable) replacement for the C library function 436 <tt>memset(dst, c, len)</tt>. Please note the different 437 order of arguments! 438 </p> 439 440 <h2 id="target">Target-specific Information</h2> 441 442 <h3 id="ffi_abi"><tt>status = ffi.abi(param)</tt></h3> 443 <p> 444 Returns <tt>true</tt> if <tt>param</tt> (a Lua string) applies for the 445 target ABI (Application Binary Interface). Returns <tt>false</tt> 446 otherwise. The following parameters are currently defined: 447 </p> 448 <table class="abitable"> 449 <tr class="abihead"> 450 <td class="abiparam">Parameter</td> 451 <td class="abidesc">Description</td> 452 </tr> 453 <tr class="odd separate"> 454 <td class="abiparam">32bit</td><td class="abidesc">32 bit architecture</td></tr> 455 <tr class="even"> 456 <td class="abiparam">64bit</td><td class="abidesc">64 bit architecture</td></tr> 457 <tr class="odd separate"> 458 <td class="abiparam">le</td><td class="abidesc">Little-endian architecture</td></tr> 459 <tr class="even"> 460 <td class="abiparam">be</td><td class="abidesc">Big-endian architecture</td></tr> 461 <tr class="odd separate"> 462 <td class="abiparam">fpu</td><td class="abidesc">Target has a hardware FPU</td></tr> 463 <tr class="even"> 464 <td class="abiparam">softfp</td><td class="abidesc">softfp calling conventions</td></tr> 465 <tr class="odd"> 466 <td class="abiparam">hardfp</td><td class="abidesc">hardfp calling conventions</td></tr> 467 <tr class="even separate"> 468 <td class="abiparam">eabi</td><td class="abidesc">EABI variant of the standard ABI</td></tr> 469 <tr class="odd"> 470 <td class="abiparam">win</td><td class="abidesc">Windows variant of the standard ABI</td></tr> 471 <tr class="even"> 472 <td class="abiparam">gc64</td><td class="abidesc">64 bit GC references</td></tr> 473 </table> 474 475 <h3 id="ffi_os"><tt>ffi.os</tt></h3> 476 <p> 477 Contains the target OS name. Same contents as 478 <a href="ext_jit.html#jit_os"><tt>jit.os</tt></a>. 479 </p> 480 481 <h3 id="ffi_arch"><tt>ffi.arch</tt></h3> 482 <p> 483 Contains the target architecture name. Same contents as 484 <a href="ext_jit.html#jit_arch"><tt>jit.arch</tt></a>. 485 </p> 486 487 <h2 id="callback">Methods for Callbacks</h2> 488 <p> 489 The C types for <a href="ext_ffi_semantics.html#callback">callbacks</a> 490 have some extra methods: 491 </p> 492 493 <h3 id="callback_free"><tt>cb:free()</tt></h3> 494 <p> 495 Free the resources associated with a callback. The associated Lua 496 function is unanchored and may be garbage collected. The callback 497 function pointer is no longer valid and must not be called anymore 498 (it may be reused by a subsequently created callback). 499 </p> 500 501 <h3 id="callback_set"><tt>cb:set(func)</tt></h3> 502 <p> 503 Associate a new Lua function with a callback. The C type of the 504 callback and the callback function pointer are unchanged. 505 </p> 506 <p> 507 This method is useful to dynamically switch the receiver of callbacks 508 without creating a new callback each time and registering it again (e.g. 509 with a GUI library). 510 </p> 511 512 <h2 id="extended">Extended Standard Library Functions</h2> 513 <p> 514 The following standard library functions have been extended to work 515 with cdata objects: 516 </p> 517 518 <h3 id="tonumber"><tt>n = tonumber(cdata)</tt></h3> 519 <p> 520 Converts a number cdata object to a <tt>double</tt> and returns it as 521 a Lua number. This is particularly useful for boxed 64 bit 522 integer values. Caveat: this conversion may incur a precision loss. 523 </p> 524 525 <h3 id="tostring"><tt>s = tostring(cdata)</tt></h3> 526 <p> 527 Returns a string representation of the value of 64 bit integers 528 (<tt><b>"</b>nnn<b>LL"</b></tt> or <tt><b>"</b>nnn<b>ULL"</b></tt>) or 529 complex numbers (<tt><b>"</b>re±im<b>i"</b></tt>). Otherwise 530 returns a string representation of the C type of a ctype object 531 (<tt><b>"ctype<</b>type<b>>"</b></tt>) or a cdata object 532 (<tt><b>"cdata<</b>type<b>>: </b>address"</tt>), unless you 533 override it with a <tt>__tostring</tt> metamethod (see 534 <a href="#ffi_metatype"><tt>ffi.metatype()</tt></a>). 535 </p> 536 537 <h3 id="pairs"><tt>iter, obj, start = pairs(cdata)<br> 538 iter, obj, start = ipairs(cdata)<br></tt></h3> 539 <p> 540 Calls the <tt>__pairs</tt> or <tt>__ipairs</tt> metamethod of the 541 corresponding ctype. 542 </p> 543 544 <h2 id="literals">Extensions to the Lua Parser</h2> 545 <p> 546 The parser for Lua source code treats numeric literals with the 547 suffixes <tt>LL</tt> or <tt>ULL</tt> as signed or unsigned 64 bit 548 integers. Case doesn't matter, but uppercase is recommended for 549 readability. It handles decimal (<tt>42LL</tt>), hexadecimal 550 (<tt>0x2aLL</tt>) and binary (<tt>0b101010LL</tt>) literals. 551 </p> 552 <p> 553 The imaginary part of complex numbers can be specified by suffixing 554 number literals with <tt>i</tt> or <tt>I</tt>, e.g. <tt>12.5i</tt>. 555 Caveat: you'll need to use <tt>1i</tt> to get an imaginary part with 556 the value one, since <tt>i</tt> itself still refers to a variable 557 named <tt>i</tt>. 558 </p> 559 <br class="flush"> 560 </div> 561 <div id="foot"> 562 <hr class="hide"> 563 Copyright © 2005-2016 Mike Pall 564 <span class="noprint"> 565 · 566 <a href="contact.html">Contact</a> 567 </span> 568 </div> 569 </body> 570 </html>