1 <section xmlns="http://docbook.org/ns/docbook" version="5.0" 2 xml:id="std.localization.locales.locale" xreflabel="Locale"> 3 4 <info><title>locale</title> 5 <keywordset> 6 <keyword>ISO C++</keyword> 7 <keyword>locale</keyword> 8 </keywordset> 9 </info> 10 11 12 13 <para> 14 Describes the basic locale object, including nested 15 classes id, facet, and the reference-counted implementation object, 16 class _Impl. 17 </para> 18 19 <section xml:id="locales.locale.req"><info><title>Requirements</title></info> 20 21 22 <para> 23 Class locale is non-templatized and has two distinct types nested 24 inside of it: 25 </para> 26 27 <blockquote> 28 <para> 29 <emphasis> 30 class facet 31 22.1.1.1.2 Class locale::facet 32 </emphasis> 33 </para> 34 </blockquote> 35 36 <para> 37 Facets actually implement locale functionality. For instance, a facet 38 called numpunct is the data object that can be used to query for the 39 thousands separator in the locale. 40 </para> 41 42 <para> 43 Literally, a facet is strictly defined: 44 </para> 45 46 <itemizedlist> 47 <listitem> 48 <para> 49 Containing the following public data member: 50 </para> 51 <para> 52 <code>static locale::id id;</code> 53 </para> 54 </listitem> 55 56 <listitem> 57 <para> 58 Derived from another facet: 59 </para> 60 <para> 61 <code>class gnu_codecvt: public std::ctype<user-defined-type></code> 62 </para> 63 </listitem> 64 </itemizedlist> 65 66 <para> 67 Of interest in this class are the memory management options explicitly 68 specified as an argument to facet's constructor. Each constructor of a 69 facet class takes a std::size_t __refs argument: if __refs == 0, the 70 facet is deleted when the locale containing it is destroyed. If __refs 71 == 1, the facet is not destroyed, even when it is no longer 72 referenced. 73 </para> 74 75 <blockquote> 76 <para> 77 <emphasis> 78 class id 79 22.1.1.1.3 - Class locale::id 80 </emphasis> 81 </para> 82 </blockquote> 83 84 <para> 85 Provides an index for looking up specific facets. 86 </para> 87 </section> 88 89 <section xml:id="locales.locale.design"><info><title>Design</title></info> 90 91 92 <para> 93 The major design challenge is fitting an object-orientated and 94 non-global locale design on top of POSIX and other relevant standards, 95 which include the Single Unix (nee X/Open.) 96 </para> 97 98 <para> 99 Because C and earlier versions of POSIX fall down so completely, 100 portability is an issue. 101 </para> 102 103 </section> 104 105 <section xml:id="locales.locale.impl"><info><title>Implementation</title></info> 106 107 108 <section xml:id="locale.impl.c"><info><title>Interacting with "C" locales</title></info> 109 110 111 <itemizedlist> 112 <listitem> 113 <para> 114 <code>locale -a</code> displays available locales. 115 </para> 116 <blockquote> 117 <programlisting> 118 af_ZA 119 ar_AE 120 ar_AE.utf8 121 ar_BH 122 ar_BH.utf8 123 ar_DZ 124 ar_DZ.utf8 125 ar_EG 126 ar_EG.utf8 127 ar_IN 128 ar_IQ 129 ar_IQ.utf8 130 ar_JO 131 ar_JO.utf8 132 ar_KW 133 ar_KW.utf8 134 ar_LB 135 ar_LB.utf8 136 ar_LY 137 ar_LY.utf8 138 ar_MA 139 ar_MA.utf8 140 ar_OM 141 ar_OM.utf8 142 ar_QA 143 ar_QA.utf8 144 ar_SA 145 ar_SA.utf8 146 ar_SD 147 ar_SD.utf8 148 ar_SY 149 ar_SY.utf8 150 ar_TN 151 ar_TN.utf8 152 ar_YE 153 ar_YE.utf8 154 be_BY 155 be_BY.utf8 156 bg_BG 157 bg_BG.utf8 158 br_FR 159 bs_BA 160 C 161 ca_ES 162 ca_ES@euro 163 ca_ES.utf8 164 ca_ES.utf8@euro 165 cs_CZ 166 cs_CZ.utf8 167 cy_GB 168 da_DK 169 da_DK.iso885915 170 da_DK.utf8 171 de_AT 172 de_AT@euro 173 de_AT.utf8 174 de_AT.utf8@euro 175 de_BE 176 de_BE@euro 177 de_BE.utf8 178 de_BE.utf8@euro 179 de_CH 180 de_CH.utf8 181 de_DE 182 de_DE@euro 183 de_DE.utf8 184 de_DE.utf8@euro 185 de_LU 186 de_LU@euro 187 de_LU.utf8 188 de_LU.utf8@euro 189 el_GR 190 el_GR.utf8 191 en_AU 192 en_AU.utf8 193 en_BW 194 en_BW.utf8 195 en_CA 196 en_CA.utf8 197 en_DK 198 en_DK.utf8 199 en_GB 200 en_GB.iso885915 201 en_GB.utf8 202 en_HK 203 en_HK.utf8 204 en_IE 205 en_IE@euro 206 en_IE.utf8 207 en_IE.utf8@euro 208 en_IN 209 en_NZ 210 en_NZ.utf8 211 en_PH 212 en_PH.utf8 213 en_SG 214 en_SG.utf8 215 en_US 216 en_US.iso885915 217 en_US.utf8 218 en_ZA 219 en_ZA.utf8 220 en_ZW 221 en_ZW.utf8 222 es_AR 223 es_AR.utf8 224 es_BO 225 es_BO.utf8 226 es_CL 227 es_CL.utf8 228 es_CO 229 es_CO.utf8 230 es_CR 231 es_CR.utf8 232 es_DO 233 es_DO.utf8 234 es_EC 235 es_EC.utf8 236 es_ES 237 es_ES@euro 238 es_ES.utf8 239 es_ES.utf8@euro 240 es_GT 241 es_GT.utf8 242 es_HN 243 es_HN.utf8 244 es_MX 245 es_MX.utf8 246 es_NI 247 es_NI.utf8 248 es_PA 249 es_PA.utf8 250 es_PE 251 es_PE.utf8 252 es_PR 253 es_PR.utf8 254 es_PY 255 es_PY.utf8 256 es_SV 257 es_SV.utf8 258 es_US 259 es_US.utf8 260 es_UY 261 es_UY.utf8 262 es_VE 263 es_VE.utf8 264 et_EE 265 et_EE.utf8 266 eu_ES 267 eu_ES@euro 268 eu_ES.utf8 269 eu_ES.utf8@euro 270 fa_IR 271 fi_FI 272 fi_FI@euro 273 fi_FI.utf8 274 fi_FI.utf8@euro 275 fo_FO 276 fo_FO.utf8 277 fr_BE 278 fr_BE@euro 279 fr_BE.utf8 280 fr_BE.utf8@euro 281 fr_CA 282 fr_CA.utf8 283 fr_CH 284 fr_CH.utf8 285 fr_FR 286 fr_FR@euro 287 fr_FR.utf8 288 fr_FR.utf8@euro 289 fr_LU 290 fr_LU@euro 291 fr_LU.utf8 292 fr_LU.utf8@euro 293 ga_IE 294 ga_IE@euro 295 ga_IE.utf8 296 ga_IE.utf8@euro 297 gl_ES 298 gl_ES@euro 299 gl_ES.utf8 300 gl_ES.utf8@euro 301 gv_GB 302 gv_GB.utf8 303 he_IL 304 he_IL.utf8 305 hi_IN 306 hr_HR 307 hr_HR.utf8 308 hu_HU 309 hu_HU.utf8 310 id_ID 311 id_ID.utf8 312 is_IS 313 is_IS.utf8 314 it_CH 315 it_CH.utf8 316 it_IT 317 it_IT@euro 318 it_IT.utf8 319 it_IT.utf8@euro 320 iw_IL 321 iw_IL.utf8 322 ja_JP.eucjp 323 ja_JP.utf8 324 ka_GE 325 kl_GL 326 kl_GL.utf8 327 ko_KR.euckr 328 ko_KR.utf8 329 kw_GB 330 kw_GB.utf8 331 lt_LT 332 lt_LT.utf8 333 lv_LV 334 lv_LV.utf8 335 mi_NZ 336 mk_MK 337 mk_MK.utf8 338 mr_IN 339 ms_MY 340 ms_MY.utf8 341 mt_MT 342 mt_MT.utf8 343 nl_BE 344 nl_BE@euro 345 nl_BE.utf8 346 nl_BE.utf8@euro 347 nl_NL 348 nl_NL@euro 349 nl_NL.utf8 350 nl_NL.utf8@euro 351 nn_NO 352 nn_NO.utf8 353 no_NO 354 no_NO.utf8 355 oc_FR 356 pl_PL 357 pl_PL.utf8 358 POSIX 359 pt_BR 360 pt_BR.utf8 361 pt_PT 362 pt_PT@euro 363 pt_PT.utf8 364 pt_PT.utf8@euro 365 ro_RO 366 ro_RO.utf8 367 ru_RU 368 ru_RU.koi8r 369 ru_RU.utf8 370 ru_UA 371 ru_UA.utf8 372 se_NO 373 sk_SK 374 sk_SK.utf8 375 sl_SI 376 sl_SI.utf8 377 sq_AL 378 sq_AL.utf8 379 sr_YU 380 sr_YU@cyrillic 381 sr_YU.utf8 382 sr_YU.utf8@cyrillic 383 sv_FI 384 sv_FI@euro 385 sv_FI.utf8 386 sv_FI.utf8@euro 387 sv_SE 388 sv_SE.iso885915 389 sv_SE.utf8 390 ta_IN 391 te_IN 392 tg_TJ 393 th_TH 394 th_TH.utf8 395 tl_PH 396 tr_TR 397 tr_TR.utf8 398 uk_UA 399 uk_UA.utf8 400 ur_PK 401 uz_UZ 402 vi_VN 403 vi_VN.tcvn 404 wa_BE 405 wa_BE@euro 406 yi_US 407 zh_CN 408 zh_CN.gb18030 409 zh_CN.gbk 410 zh_CN.utf8 411 zh_HK 412 zh_HK.utf8 413 zh_TW 414 zh_TW.euctw 415 zh_TW.utf8 416 </programlisting> 417 </blockquote> 418 </listitem> 419 420 <listitem> 421 <para> 422 <code>`locale`</code> displays environmental variables that 423 impact how locale("") will be deduced. 424 </para> 425 <blockquote> 426 <programlisting> 427 LANG=en_US 428 LC_CTYPE="en_US" 429 LC_NUMERIC="en_US" 430 LC_TIME="en_US" 431 LC_COLLATE="en_US" 432 LC_MONETARY="en_US" 433 LC_MESSAGES="en_US" 434 LC_PAPER="en_US" 435 LC_NAME="en_US" 436 LC_ADDRESS="en_US" 437 LC_TELEPHONE="en_US" 438 LC_MEASUREMENT="en_US" 439 LC_IDENTIFICATION="en_US" 440 LC_ALL= 441 </programlisting> 442 </blockquote> 443 </listitem> 444 </itemizedlist> 445 446 <para> 447 From Josuttis, p. 697-698, which says, that "there is only *one* 448 relation (of the C++ locale mechanism) to the C locale mechanism: the 449 global C locale is modified if a named C++ locale object is set as the 450 global locale" (emphasis Paolo), that is: 451 </para> 452 453 <programlisting>std::locale::global(std::locale(""));</programlisting> 454 455 <para>affects the C functions as if the following call was made:</para> 456 457 <programlisting>std::setlocale(LC_ALL, "");</programlisting> 458 459 <para> 460 On the other hand, there is *no* vice versa, that is, calling 461 setlocale has *no* whatsoever on the C++ locale mechanism, in 462 particular on the working of locale(""), which constructs the locale 463 object from the environment of the running program, that is, in 464 practice, the set of LC_ALL, LANG, etc. variable of the shell. 465 </para> 466 467 </section> 468 </section> 469 470 <section xml:id="locales.locale.future"><info><title>Future</title></info> 471 472 473 <itemizedlist> 474 <listitem> 475 <para> 476 Locale initialization: at what point does _S_classic, _S_global 477 get initialized? Can named locales assume this initialization 478 has already taken place? 479 </para> 480 </listitem> 481 482 <listitem> 483 <para> 484 Document how named locales error check when filling data 485 members. I.e., a fr_FR locale that doesn't have 486 numpunct::truename(): does it use "true"? Or is it a blank 487 string? What's the convention? 488 </para> 489 </listitem> 490 491 <listitem> 492 <para> 493 Explain how locale aliasing happens. When does "de_DE" use "de" 494 information? What is the rule for locales composed of just an 495 ISO language code (say, "de") and locales with both an ISO 496 language code and ISO country code (say, "de_DE"). 497 </para> 498 </listitem> 499 500 <listitem> 501 <para> 502 What should non-required facet instantiations do? If the 503 generic implementation is provided, then how to end-users 504 provide specializations? 505 </para> 506 </listitem> 507 </itemizedlist> 508 </section> 509 510 <bibliography xml:id="locales.locale.biblio"><info><title>Bibliography</title></info> 511 512 513 <biblioentry> 514 <citetitle> 515 The GNU C Library 516 </citetitle> 517 <author><personname><surname>McGrath</surname><firstname>Roland</firstname></personname></author> 518 <author><personname><surname>Drepper</surname><firstname>Ulrich</firstname></personname></author> 519 <copyright> 520 <year>2007</year> 521 <holder>FSF</holder> 522 </copyright> 523 <pagenums> 524 Chapters 6 Character Set Handling and 7 Locales and 525 Internationalization 526 </pagenums> 527 </biblioentry> 528 529 <biblioentry> 530 <citetitle> 531 Correspondence 532 </citetitle> 533 <author><personname><surname>Drepper</surname><firstname>Ulrich</firstname></personname></author> 534 <copyright> 535 <year>2002</year> 536 <holder/> 537 </copyright> 538 </biblioentry> 539 540 <biblioentry> 541 <citetitle> 542 ISO/IEC 14882:1998 Programming languages - C++ 543 </citetitle> 544 <copyright> 545 <year>1998</year> 546 <holder>ISO</holder> 547 </copyright> 548 </biblioentry> 549 550 <biblioentry> 551 <citetitle> 552 ISO/IEC 9899:1999 Programming languages - C 553 </citetitle> 554 <copyright> 555 <year>1999</year> 556 <holder>ISO</holder> 557 </copyright> 558 </biblioentry> 559 560 <biblioentry> 561 <title> 562 <link xmlns:xlink="http://www.w3.org/1999/xlink" 563 xlink:href="https://pubs.opengroup.org/onlinepubs/9699919799/"> 564 System Interface Definitions, Issue 7 (IEEE Std. 1003.1-2008) 565 </link> 566 </title> 567 <copyright> 568 <year>2008</year> 569 <holder> 570 The Open Group/The Institute of Electrical and Electronics 571 Engineers, Inc. 572 </holder> 573 </copyright> 574 </biblioentry> 575 576 <biblioentry> 577 <citetitle> 578 The C++ Programming Language, Special Edition 579 </citetitle> 580 <author><personname><surname>Stroustrup</surname><firstname>Bjarne</firstname></personname></author> 581 <copyright> 582 <year>2000</year> 583 <holder>Addison Wesley, Inc.</holder> 584 </copyright> 585 <pagenums>Appendix D</pagenums> 586 <publisher> 587 <publishername> 588 Addison Wesley 589 </publishername> 590 </publisher> 591 </biblioentry> 592 593 <biblioentry> 594 <citetitle> 595 Standard C++ IOStreams and Locales 596 </citetitle> 597 <subtitle> 598 Advanced Programmer's Guide and Reference 599 </subtitle> 600 <author><personname><surname>Langer</surname><firstname>Angelika</firstname></personname></author> 601 <author><personname><surname>Kreft</surname><firstname>Klaus</firstname></personname></author> 602 <copyright> 603 <year>2000</year> 604 <holder>Addison Wesley Longman, Inc.</holder> 605 </copyright> 606 <publisher> 607 <publishername> 608 Addison Wesley Longman 609 </publishername> 610 </publisher> 611 </biblioentry> 612 613 </bibliography> 614 615 </section> 616
Indexes created Fri Jun 12 00:25:51 UTC 2026