icuSources/samples/ustring/ustring.cpp

   1 /*
   2 *******************************************************************************
   3 *
   4 *   © 2016 and later: Unicode, Inc. and others.
   5 *   License & terms of use: http://www.unicode.org/copyright.html#License
   6 *
   7 *******************************************************************************
   8 *******************************************************************************
   9 *
  10 *   Copyright (C) 2000-2014, International Business Machines
  11 *   Corporation and others.  All Rights Reserved.
  12 *
  13 *******************************************************************************
  14 *   file name:  ustring.c
  15 *   encoding:   UTF-8
  16 *   tab size:   8 (not used)
  17 *   indentation:4
  18 *
  19 *   created on: 2000aug15
  20 *   created by: Markus W. Scherer
  21 *
  22 *   This file contains sample code that illustrates the use of Unicode strings
  23 *   with ICU.
  24 */
  25
  26 #include <stdio.h>
  27 #include "unicode/utypes.h"
  28 #include "unicode/uchar.h"
  29 #include "unicode/locid.h"
  30 #include "unicode/ustring.h"
  31 #include "unicode/ucnv.h"
  32 #include "unicode/unistr.h"
  33
  34 #ifndef UPRV_LENGTHOF
  35 #define UPRV_LENGTHOF(array) (int32_t)(sizeof(array)/sizeof((array)[0]))
  36 #endif
  37
  38 // helper functions -------------------------------------------------------- ***
  39
  40 // default converter for the platform encoding
  41 static UConverter *cnv=NULL;
  42
  43 static void
  44 printUString(const char *announce, const UChar *s, int32_t length) {
  45     static char out[200];
  46     UChar32 c;
  47     int32_t i;
  48     UErrorCode errorCode=U_ZERO_ERROR;
  49
  50     /*
  51      * Convert to the "platform encoding". See notes in printUnicodeString().
  52      * ucnv_fromUChars(), like most ICU APIs understands length==-1
  53      * to mean that the string is NUL-terminated.
  54      */
  55     ucnv_fromUChars(cnv, out, sizeof(out), s, length, &errorCode);
  56     if(U_FAILURE(errorCode) || errorCode==U_STRING_NOT_TERMINATED_WARNING) {
  57         printf("%sproblem converting string from Unicode: %s\n", announce, u_errorName(errorCode));
  58         return;
  59     }
  60
  61     printf("%s%s {", announce, out);
  62
  63     /* output the code points (not code units) */
  64     if(length>=0) {
  65         /* s is not NUL-terminated */
  66         for(i=0; i<length; /* U16_NEXT post-increments */) {
  67             U16_NEXT(s, i, length, c);
  68             printf(" %04x", c);
  69         }
  70     } else {
  71         /* s is NUL-terminated */
  72         for(i=0; /* condition in loop body */; /* U16_NEXT post-increments */) {
  73             U16_NEXT(s, i, length, c);
  74             if(c==0) {
  75                 break;
  76             }
  77             printf(" %04x", c);
  78         }
  79     }
  80     printf(" }\n");
  81 }
  82
  83 static void
  84 printUnicodeString(const char *announce, const UnicodeString &s) {
  85     static char out[200];
  86     int32_t i, length;
  87
  88     // output the string, converted to the platform encoding
  89
  90     // Note for Windows: The "platform encoding" defaults to the "ANSI codepage",
  91     // which is different from the "OEM codepage" in the console window.
  92     // However, if you pipe the output into a file and look at it with Notepad
  93     // or similar, then "ANSI" characters will show correctly.
  94     // Production code should be aware of what encoding is required,
  95     // and use a UConverter or at least a charset name explicitly.
  96     out[s.extract(0, 99, out)]=0;
  97     printf("%s%s {", announce, out);
  98
  99     // output the code units (not code points)
 100     length=s.length();
 101     for(i=0; i<length; ++i) {
 102         printf(" %04x", s.charAt(i));
 103     }
 104     printf(" }\n");
 105 }
 106
 107 // sample code for utf.h macros -------------------------------------------- ***
 108
 109 static void
 110 demo_utf_h_macros() {
 111     static UChar input[]={ 0x0061, 0xd800, 0xdc00, 0xdbff, 0xdfff, 0x0062 };
 112     UChar32 c;
 113     int32_t i;
 114     UBool isError;
 115
 116     printf("\n* demo_utf_h_macros() -------------- ***\n\n");
 117
 118     printUString("iterate forward through: ", input, UPRV_LENGTHOF(input));
 119     for(i=0; i<UPRV_LENGTHOF(input); /* U16_NEXT post-increments */) {
 120         /* Iterating forwards
 121            Codepoint at offset 0: U+0061
 122            Codepoint at offset 1: U+10000
 123            Codepoint at offset 3: U+10ffff
 124            Codepoint at offset 5: U+0062
 125         */
 126         printf("Codepoint at offset %d: U+", i);
 127         U16_NEXT(input, i, UPRV_LENGTHOF(input), c);
 128         printf("%04x\n", c);
 129     }
 130
 131     puts("");
 132
 133     isError=FALSE;
 134     i=1; /* write position, gets post-incremented so needs to be in an l-value */
 135     U16_APPEND(input, i, UPRV_LENGTHOF(input), 0x0062, isError);
 136
 137     printUString("iterate backward through: ", input, UPRV_LENGTHOF(input));
 138     for(i=UPRV_LENGTHOF(input); i>0; /* U16_PREV pre-decrements */) {
 139         U16_PREV(input, 0, i, c);
 140         /* Iterating backwards
 141            Codepoint at offset 5: U+0062
 142            Codepoint at offset 3: U+10ffff
 143            Codepoint at offset 2: U+dc00 -- unpaired surrogate because lead surr. overwritten
 144            Codepoint at offset 1: U+0062 -- by this BMP code point
 145            Codepoint at offset 0: U+0061
 146         */
 147         printf("Codepoint at offset %d: U+%04x\n", i, c);
 148     }
 149 }
 150
 151 // sample code for Unicode strings in C ------------------------------------ ***
 152
 153 static void demo_C_Unicode_strings() {
 154     printf("\n* demo_C_Unicode_strings() --------- ***\n\n");
 155
 156     static const UChar text[]={ 0x41, 0x42, 0x43, 0 };          /* "ABC" */
 157     static const UChar appendText[]={ 0x61, 0x62, 0x63, 0 };    /* "abc" */
 158     static const UChar cmpText[]={ 0x61, 0x53, 0x73, 0x43, 0 }; /* "aSsC" */
 159     UChar buffer[32];
 160     int32_t compare;
 161     int32_t length=u_strlen(text); /* length=3 */
 162
 163     /* simple ANSI C-style functions */
 164     buffer[0]=0;                    /* empty, NUL-terminated string */
 165     u_strncat(buffer, text, 1);     /* append just n=1 character ('A') */
 166     u_strcat(buffer, appendText);   /* buffer=="Aabc" */
 167     length=u_strlen(buffer);        /* length=4 */
 168     printUString("should be \"Aabc\": ", buffer, -1);
 169
 170     /* bitwise comparing buffer with text */
 171     compare=u_strcmp(buffer, text);
 172     if(compare<=0) {
 173         printf("String comparison error, expected \"Aabc\" > \"ABC\"\n");
 174     }
 175
 176     /* Build "A<sharp s>C" in the buffer... */
 177     u_strcpy(buffer, text);
 178     buffer[1]=0xdf; /* sharp s, case-compares equal to "ss" */
 179     printUString("should be \"A<sharp s>C\": ", buffer, -1);
 180
 181     /* Compare two strings case-insensitively using full case folding */
 182     compare=u_strcasecmp(buffer, cmpText, U_FOLD_CASE_DEFAULT);
 183     if(compare!=0) {
 184         printf("String case insensitive comparison error, expected \"AbC\" to be equal to \"ABC\"\n");
 185     }
 186 }
 187
 188 // sample code for case mappings with C APIs -------------------------------- ***
 189
 190 static void demoCaseMapInC() {
 191     /*
 192      * input=
 193      *   "aB<capital sigma>"
 194      *   "iI<small dotless i><capital dotted I> "
 195      *   "<sharp s> <small lig. ffi>"
 196      *   "<small final sigma><small sigma><capital sigma>"
 197      */
 198     static const UChar input[]={
 199         0x61, 0x42, 0x3a3,
 200         0x69, 0x49, 0x131, 0x130, 0x20,
 201         0xdf, 0x20, 0xfb03,
 202         0x3c2, 0x3c3, 0x3a3, 0
 203     };
 204     UChar buffer[32];
 205
 206     UErrorCode errorCode;
 207     UChar32 c;
 208     int32_t i, j, length;
 209     UBool isError;
 210
 211     printf("\n* demoCaseMapInC() ----------------- ***\n\n");
 212
 213     /*
 214      * First, use simple case mapping functions which provide
 215      * 1:1 code point mappings without context/locale ID.
 216      *
 217      * Note that some mappings will not be "right" because some "real"
 218      * case mappings require context, depend on the locale ID,
 219      * and/or result in a change in the number of code points.
 220      */
 221     printUString("input string: ", input, -1);
 222
 223     /* uppercase */
 224     isError=FALSE;
 225     for(i=j=0; j<UPRV_LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
 226         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
 227         if(c==0) {
 228             break; /* stop at terminating NUL, no need to terminate buffer */
 229         }
 230         c=u_toupper(c);
 231         U16_APPEND(buffer, j, UPRV_LENGTHOF(buffer), c, isError);
 232     }
 233     printUString("simple-uppercased: ", buffer, j);
 234     /* lowercase */
 235     isError=FALSE;
 236     for(i=j=0; j<UPRV_LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
 237         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
 238         if(c==0) {
 239             break; /* stop at terminating NUL, no need to terminate buffer */
 240         }
 241         c=u_tolower(c);
 242         U16_APPEND(buffer, j, UPRV_LENGTHOF(buffer), c, isError);
 243     }
 244     printUString("simple-lowercased: ", buffer, j);
 245     /* titlecase */
 246     isError=FALSE;
 247     for(i=j=0; j<UPRV_LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
 248         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
 249         if(c==0) {
 250             break; /* stop at terminating NUL, no need to terminate buffer */
 251         }
 252         c=u_totitle(c);
 253         U16_APPEND(buffer, j, UPRV_LENGTHOF(buffer), c, isError);
 254     }
 255     printUString("simple-titlecased: ", buffer, j);
 256     /* case-fold/default */
 257     isError=FALSE;
 258     for(i=j=0; j<UPRV_LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
 259         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
 260         if(c==0) {
 261             break; /* stop at terminating NUL, no need to terminate buffer */
 262         }
 263         c=u_foldCase(c, U_FOLD_CASE_DEFAULT);
 264         U16_APPEND(buffer, j, UPRV_LENGTHOF(buffer), c, isError);
 265     }
 266     printUString("simple-case-folded/default: ", buffer, j);
 267     /* case-fold/Turkic */
 268     isError=FALSE;
 269     for(i=j=0; j<UPRV_LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
 270         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
 271         if(c==0) {
 272             break; /* stop at terminating NUL, no need to terminate buffer */
 273         }
 274         c=u_foldCase(c, U_FOLD_CASE_EXCLUDE_SPECIAL_I);
 275         U16_APPEND(buffer, j, UPRV_LENGTHOF(buffer), c, isError);
 276     }
 277     printUString("simple-case-folded/Turkic: ", buffer, j);
 278
 279     /*
 280      * Second, use full case mapping functions which provide
 281      * 1:n code point mappings (n can be 0!) and are sensitive to context and locale ID.
 282      *
 283      * Note that lower/upper/titlecasing take a locale ID while case-folding
 284      * has bit flag options instead, by design of the Unicode SpecialCasing.txt UCD file.
 285      *
 286      * Also, string titlecasing requires a BreakIterator to find starts of words.
 287      * The sample code here passes in a NULL pointer; u_strToTitle() will open and close a default
 288      * titlecasing BreakIterator automatically.
 289      * For production code where many strings are titlecased it would be more efficient
 290      * to open a BreakIterator externally and pass it in.
 291      */
 292     printUString("\ninput string: ", input, -1);
 293
 294     /* lowercase/English */
 295     errorCode=U_ZERO_ERROR;
 296     length=u_strToLower(buffer, UPRV_LENGTHOF(buffer), input, -1, "en", &errorCode);
 297     if(U_SUCCESS(errorCode)) {
 298         printUString("full-lowercased/en: ", buffer, length);
 299     } else {
 300         printf("error in u_strToLower(en)=%ld error=%s\n", length, u_errorName(errorCode));
 301     }
 302     /* lowercase/Turkish */
 303     errorCode=U_ZERO_ERROR;
 304     length=u_strToLower(buffer, UPRV_LENGTHOF(buffer), input, -1, "tr", &errorCode);
 305     if(U_SUCCESS(errorCode)) {
 306         printUString("full-lowercased/tr: ", buffer, length);
 307     } else {
 308         printf("error in u_strToLower(tr)=%ld error=%s\n", length, u_errorName(errorCode));
 309     }
 310     /* uppercase/English */
 311     errorCode=U_ZERO_ERROR;
 312     length=u_strToUpper(buffer, UPRV_LENGTHOF(buffer), input, -1, "en", &errorCode);
 313     if(U_SUCCESS(errorCode)) {
 314         printUString("full-uppercased/en: ", buffer, length);
 315     } else {
 316         printf("error in u_strToUpper(en)=%ld error=%s\n", length, u_errorName(errorCode));
 317     }
 318     /* uppercase/Turkish */
 319     errorCode=U_ZERO_ERROR;
 320     length=u_strToUpper(buffer, UPRV_LENGTHOF(buffer), input, -1, "tr", &errorCode);
 321     if(U_SUCCESS(errorCode)) {
 322         printUString("full-uppercased/tr: ", buffer, length);
 323     } else {
 324         printf("error in u_strToUpper(tr)=%ld error=%s\n", length, u_errorName(errorCode));
 325     }
 326     /* titlecase/English */
 327     errorCode=U_ZERO_ERROR;
 328     length=u_strToTitle(buffer, UPRV_LENGTHOF(buffer), input, -1, NULL, "en", &errorCode);
 329     if(U_SUCCESS(errorCode)) {
 330         printUString("full-titlecased/en: ", buffer, length);
 331     } else {
 332         printf("error in u_strToTitle(en)=%ld error=%s\n", length, u_errorName(errorCode));
 333     }
 334     /* titlecase/Turkish */
 335     errorCode=U_ZERO_ERROR;
 336     length=u_strToTitle(buffer, UPRV_LENGTHOF(buffer), input, -1, NULL, "tr", &errorCode);
 337     if(U_SUCCESS(errorCode)) {
 338         printUString("full-titlecased/tr: ", buffer, length);
 339     } else {
 340         printf("error in u_strToTitle(tr)=%ld error=%s\n", length, u_errorName(errorCode));
 341     }
 342     /* case-fold/default */
 343     errorCode=U_ZERO_ERROR;
 344     length=u_strFoldCase(buffer, UPRV_LENGTHOF(buffer), input, -1, U_FOLD_CASE_DEFAULT, &errorCode);
 345     if(U_SUCCESS(errorCode)) {
 346         printUString("full-case-folded/default: ", buffer, length);
 347     } else {
 348         printf("error in u_strFoldCase(default)=%ld error=%s\n", length, u_errorName(errorCode));
 349     }
 350     /* case-fold/Turkic */
 351     errorCode=U_ZERO_ERROR;
 352     length=u_strFoldCase(buffer, UPRV_LENGTHOF(buffer), input, -1, U_FOLD_CASE_EXCLUDE_SPECIAL_I, &errorCode);
 353     if(U_SUCCESS(errorCode)) {
 354         printUString("full-case-folded/Turkic: ", buffer, length);
 355     } else {
 356         printf("error in u_strFoldCase(Turkic)=%ld error=%s\n", length, u_errorName(errorCode));
 357     }
 358 }
 359
 360 // sample code for case mappings with C++ APIs ------------------------------ ***
 361
 362 static void demoCaseMapInCPlusPlus() {
 363     /*
 364      * input=
 365      *   "aB<capital sigma>"
 366      *   "iI<small dotless i><capital dotted I> "
 367      *   "<sharp s> <small lig. ffi>"
 368      *   "<small final sigma><small sigma><capital sigma>"
 369      */
 370     static const UChar input[]={
 371         0x61, 0x42, 0x3a3,
 372         0x69, 0x49, 0x131, 0x130, 0x20,
 373         0xdf, 0x20, 0xfb03,
 374         0x3c2, 0x3c3, 0x3a3, 0
 375     };
 376
 377     printf("\n* demoCaseMapInCPlusPlus() --------- ***\n\n");
 378
 379     UnicodeString s(input), t;
 380     const Locale &en=Locale::getEnglish();
 381     Locale tr("tr");
 382
 383     /*
 384      * Full case mappings as in demoCaseMapInC(), using UnicodeString functions.
 385      * These functions modify the string object itself.
 386      * Since we want to keep the input string around, we copy it each time
 387      * and case-map the copy.
 388      */
 389     printUnicodeString("input string: ", s);
 390
 391     /* lowercase/English */
 392     printUnicodeString("full-lowercased/en: ", (t=s).toLower(en));
 393     /* lowercase/Turkish */
 394     printUnicodeString("full-lowercased/tr: ", (t=s).toLower(tr));
 395     /* uppercase/English */
 396     printUnicodeString("full-uppercased/en: ", (t=s).toUpper(en));
 397     /* uppercase/Turkish */
 398     printUnicodeString("full-uppercased/tr: ", (t=s).toUpper(tr));
 399     /* titlecase/English */
 400     printUnicodeString("full-titlecased/en: ", (t=s).toTitle(NULL, en));
 401     /* titlecase/Turkish */
 402     printUnicodeString("full-titlecased/tr: ", (t=s).toTitle(NULL, tr));
 403     /* case-folde/default */
 404     printUnicodeString("full-case-folded/default: ", (t=s).foldCase(U_FOLD_CASE_DEFAULT));
 405     /* case-folde/Turkic */
 406     printUnicodeString("full-case-folded/Turkic: ", (t=s).foldCase(U_FOLD_CASE_EXCLUDE_SPECIAL_I));
 407 }
 408
 409 // sample code for UnicodeString storage models ----------------------------- ***
 410
 411 static const UChar readonly[]={
 412     0x61, 0x31, 0x20ac
 413 };
 414 static UChar writeable[]={
 415     0x62, 0x32, 0xdbc0, 0xdc01 // includes a surrogate pair for a supplementary code point
 416 };
 417 static char out[100];
 418
 419 static void
 420 demoUnicodeStringStorage() {
 421     // These sample code lines illustrate how to use UnicodeString, and the
 422     // comments tell what happens internally. There are no APIs to observe
 423     // most of this programmatically, except for stepping into the code
 424     // with a debugger.
 425     // This is by design to hide such details from the user.
 426     int32_t i;
 427
 428     printf("\n* demoUnicodeStringStorage() ------- ***\n\n");
 429
 430     // * UnicodeString with internally stored contents
 431     // instantiate a UnicodeString from a single code point
 432     // the few (2) UChars will be stored in the object itself
 433     UnicodeString one((UChar32)0x24001);
 434     // this copies the few UChars into the "two" object
 435     UnicodeString two=one;
 436     printf("length of short string copy: %d\n", two.length());
 437     // set "one" to contain the 3 UChars from readonly
 438     // this setTo() variant copies the characters
 439     one.setTo(readonly, UPRV_LENGTHOF(readonly));
 440
 441     // * UnicodeString with allocated contents
 442     // build a longer string that will not fit into the object's buffer
 443     one+=UnicodeString(writeable, UPRV_LENGTHOF(writeable));
 444     one+=one;
 445     one+=one;
 446     printf("length of longer string: %d\n", one.length());
 447     // copying will use the same allocated buffer and increment the reference
 448     // counter
 449     two=one;
 450     printf("length of longer string copy: %d\n", two.length());
 451
 452     // * UnicodeString using readonly-alias to a const UChar array
 453     // construct a string that aliases a readonly buffer
 454     UnicodeString three(FALSE, readonly, UPRV_LENGTHOF(readonly));
 455     printUnicodeString("readonly-alias string: ", three);
 456     // copy-on-write: any modification to the string results in
 457     // a copy to either the internal buffer or to a newly allocated one
 458     three.setCharAt(1, 0x39);
 459     printUnicodeString("readonly-aliasing string after modification: ", three);
 460     // the aliased array is not modified
 461     for(i=0; i<three.length(); ++i) {
 462         printf("readonly buffer[%d] after modifying its string: 0x%lx\n",
 463                i, readonly[i]);
 464     }
 465     // setTo() readonly alias
 466     one.setTo(FALSE, writeable, UPRV_LENGTHOF(writeable));
 467     // copying the readonly-alias object with fastCopyFrom() (new in ICU 2.4)
 468     // will readonly-alias the same buffer
 469     two.fastCopyFrom(one);
 470     printUnicodeString("fastCopyFrom(readonly alias of \"writeable\" array): ", two);
 471     printf("verify that a fastCopyFrom(readonly alias) uses the same buffer pointer: %d (should be 1)\n",
 472         one.getBuffer()==two.getBuffer());
 473     // a normal assignment will clone the contents (new in ICU 2.4)
 474     two=one;
 475     printf("verify that a regular copy of a readonly alias uses a different buffer pointer: %d (should be 0)\n",
 476         one.getBuffer()==two.getBuffer());
 477
 478     // * UnicodeString using writeable-alias to a non-const UChar array
 479     UnicodeString four(writeable, UPRV_LENGTHOF(writeable), UPRV_LENGTHOF(writeable));
 480     printUnicodeString("writeable-alias string: ", four);
 481     // a modification writes through to the buffer
 482     four.setCharAt(1, 0x39);
 483     for(i=0; i<four.length(); ++i) {
 484         printf("writeable-alias backing buffer[%d]=0x%lx "
 485                "after modification\n", i, writeable[i]);
 486     }
 487     // a copy will not alias any more;
 488     // instead, it will get a copy of the contents into allocated memory
 489     two=four;
 490     two.setCharAt(1, 0x21);
 491     for(i=0; i<two.length(); ++i) {
 492         printf("writeable-alias backing buffer[%d]=0x%lx after "
 493                "modification of string copy\n", i, writeable[i]);
 494     }
 495     // setTo() writeable alias, capacity==length
 496     one.setTo(writeable, UPRV_LENGTHOF(writeable), UPRV_LENGTHOF(writeable));
 497     // grow the string - it will not fit into the backing buffer any more
 498     // and will get copied before modification
 499     one.append((UChar)0x40);
 500     // shrink it back so it would fit
 501     one.truncate(one.length()-1);
 502     // we still operate on the copy
 503     one.setCharAt(1, 0x25);
 504     printf("string after growing too much and then shrinking[1]=0x%lx\n"
 505            "                          backing store for this[1]=0x%lx\n",
 506            one.charAt(1), writeable[1]);
 507     // if we need it in the original buffer, then extract() to it
 508     // extract() does not do anything if the string aliases that same buffer
 509     // i=min(one.length(), length of array)
 510     if(one.length()<UPRV_LENGTHOF(writeable)) {
 511         i=one.length();
 512     } else {
 513         i=UPRV_LENGTHOF(writeable);
 514     }
 515     one.extract(0, i, writeable);
 516     for(i=0; i<UPRV_LENGTHOF(writeable); ++i) {
 517         printf("writeable-alias backing buffer[%d]=0x%lx after re-extract\n",
 518                i, writeable[i]);
 519     }
 520 }
 521
 522 // sample code for UnicodeString instantiations ----------------------------- ***
 523
 524 static void
 525 demoUnicodeStringInit() {
 526     // *** Make sure to read about invariant characters in utypes.h! ***
 527     // Initialization of Unicode strings from C literals works _only_ for
 528     // invariant characters!
 529
 530     printf("\n* demoUnicodeStringInit() ---------- ***\n\n");
 531
 532     // the string literal is 32 chars long - this must be counted for the macro
 533     UnicodeString invariantOnly=UNICODE_STRING("such characters are safe 123 %-.", 32);
 534
 535     /*
 536      * In C, we need two macros: one to declare the UChar[] array, and
 537      * one to populate it; the second one is a noop on platforms where
 538      * wchar_t is compatible with UChar and ASCII-based.
 539      * The length of the string literal must be counted for both macros.
 540      */
 541     /* declare the invString array for the string */
 542     U_STRING_DECL(invString, "such characters are safe 123 %-.", 32);
 543     /* populate it with the characters */
 544     U_STRING_INIT(invString, "such characters are safe 123 %-.", 32);
 545
 546     // compare the C and C++ strings
 547     printf("C and C++ Unicode strings are equal: %d\n", invariantOnly==UnicodeString(TRUE, invString, 32));
 548
 549     /*
 550      * convert between char * and UChar * strings that
 551      * contain only invariant characters
 552      */
 553     static const char *cs1="such characters are safe 123 %-.";
 554     static UChar us1[40];
 555     static char cs2[40];
 556     u_charsToUChars(cs1, us1, 33); /* include the terminating NUL */
 557     u_UCharsToChars(us1, cs2, 33);
 558     printf("char * -> UChar * -> char * with only "
 559            "invariant characters: \"%s\"\n",
 560            cs2);
 561
 562     // initialize a UnicodeString from a string literal that contains
 563     // escape sequences written with invariant characters
 564     // do not forget to duplicate the backslashes for ICU to see them
 565     // then, count each double backslash only once!
 566     UnicodeString german=UNICODE_STRING(
 567         "Sch\\u00f6nes Auto: \\u20ac 11240.\\fPrivates Zeichen: \\U00102345\\n", 64).
 568         unescape();
 569     printUnicodeString("german UnicodeString from unescaping:\n    ", german);
 570
 571     /*
 572      * C: convert and unescape a char * string with only invariant
 573      * characters to fill a UChar * string
 574      */
 575     UChar buffer[200];
 576     int32_t length;
 577     length=u_unescape(
 578         "Sch\\u00f6nes Auto: \\u20ac 11240.\\fPrivates Zeichen: \\U00102345\\n",
 579         buffer, UPRV_LENGTHOF(buffer));
 580     printf("german C Unicode string from char * unescaping: (length %d)\n    ", length);
 581     printUnicodeString("", UnicodeString(buffer));
 582 }
 583
 584 extern int
 585 main(int argc, const char *argv[]) {
 586     UErrorCode errorCode=U_ZERO_ERROR;
 587
 588     // Note: Using a global variable for any object is not exactly thread-safe...
 589
 590     // You can change this call to e.g. ucnv_open("UTF-8", &errorCode) if you pipe
 591     // the output to a file and look at it with a Unicode-capable editor.
 592     // This will currently affect only the printUString() function, see the code above.
 593     // printUnicodeString() could use this, too, by changing to an extract() overload
 594     // that takes a UConverter argument.
 595     cnv=ucnv_open(NULL, &errorCode);
 596     if(U_FAILURE(errorCode)) {
 597         fprintf(stderr, "error %s opening the default converter\n", u_errorName(errorCode));
 598         return errorCode;
 599     }
 600
 601     ucnv_setFromUCallBack(cnv, UCNV_FROM_U_CALLBACK_ESCAPE, UCNV_ESCAPE_C, NULL, NULL, &errorCode);
 602     if(U_FAILURE(errorCode)) {
 603         fprintf(stderr, "error %s setting the escape callback in the default converter\n", u_errorName(errorCode));
 604         ucnv_close(cnv);
 605         return errorCode;
 606     }
 607
 608     demo_utf_h_macros();
 609     demo_C_Unicode_strings();
 610     demoCaseMapInC();
 611     demoCaseMapInCPlusPlus();
 612     demoUnicodeStringStorage();
 613     demoUnicodeStringInit();
 614
 615     ucnv_close(cnv);
 616     return 0;
 617 }