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      1 /*
      2 *******************************************************************************
      3 *
      4 *   Copyright (C) 2000-2002, International Business Machines
      5 *   Corporation and others.  All Rights Reserved.
      6 *
      7 *******************************************************************************
      8 *   file name:  ustring.c
      9 *   encoding:   US-ASCII
     10 *   tab size:   8 (not used)
     11 *   indentation:4
     12 *
     13 *   created on: 2000aug15
     14 *   created by: Markus W. Scherer
     15 *
     16 *   This file contains sample code that illustrates the use of Unicode strings
     17 *   with ICU.
     18 */
     19 
     20 #include <stdio.h>
     21 #include "unicode/utypes.h"
     22 #include "unicode/uchar.h"
     23 #include "unicode/locid.h"
     24 #include "unicode/ustring.h"
     25 #include "unicode/ucnv.h"
     26 #include "unicode/unistr.h"
     27 
     28 #define LENGTHOF(array) (sizeof(array)/sizeof((array)[0]))
     29 
     30 // helper functions -------------------------------------------------------- ***
     31 
     32 // default converter for the platform encoding
     33 static UConverter *cnv=NULL;
     34 
     35 static void
     36 printUString(const char *announce, const UChar *s, int32_t length) {
     37     static char out[200];
     38     UChar32 c;
     39     int32_t i;
     40     UErrorCode errorCode=U_ZERO_ERROR;
     41 
     42     /*
     43      * Convert to the "platform encoding". See notes in printUnicodeString().
     44      * ucnv_fromUChars(), like most ICU APIs understands length==-1
     45      * to mean that the string is NUL-terminated.
     46      */
     47     ucnv_fromUChars(cnv, out, sizeof(out), s, length, &errorCode);
     48     if(U_FAILURE(errorCode) || errorCode==U_STRING_NOT_TERMINATED_WARNING) {
     49         printf("%sproblem converting string from Unicode: %s\n", announce, u_errorName(errorCode));
     50         return;
     51     }
     52 
     53     printf("%s%s {", announce, out);
     54 
     55     /* output the code points (not code units) */
     56     if(length>=0) {
     57         /* s is not NUL-terminated */
     58         for(i=0; i<length; /* U16_NEXT post-increments */) {
     59             U16_NEXT(s, i, length, c);
     60             printf(" %04x", c);
     61         }
     62     } else {
     63         /* s is NUL-terminated */
     64         for(i=0; /* condition in loop body */; /* U16_NEXT post-increments */) {
     65             U16_NEXT(s, i, length, c);
     66             if(c==0) {
     67                 break;
     68             }
     69             printf(" %04x", c);
     70         }
     71     }
     72     printf(" }\n");
     73 }
     74 
     75 static void
     76 printUnicodeString(const char *announce, const UnicodeString &s) {
     77     static char out[200];
     78     int32_t i, length;
     79 
     80     // output the string, converted to the platform encoding
     81 
     82     // Note for Windows: The "platform encoding" defaults to the "ANSI codepage",
     83     // which is different from the "OEM codepage" in the console window.
     84     // However, if you pipe the output into a file and look at it with Notepad
     85     // or similar, then "ANSI" characters will show correctly.
     86     // Production code should be aware of what encoding is required,
     87     // and use a UConverter or at least a charset name explicitly.
     88     out[s.extract(0, 99, out)]=0;
     89     printf("%s%s {", announce, out);
     90 
     91     // output the code units (not code points)
     92     length=s.length();
     93     for(i=0; i<length; ++i) {
     94         printf(" %04x", s.charAt(i));
     95     }
     96     printf(" }\n");
     97 }
     98 
     99 // sample code for utf.h macros -------------------------------------------- ***
    100 
    101 static void
    102 demo_utf_h_macros() {
    103     static UChar input[]={ 0x0061, 0xd800, 0xdc00, 0xdbff, 0xdfff, 0x0062 };
    104     UChar32 c;
    105     int32_t i;
    106     UBool isError;
    107 
    108     printf("\n* demo_utf_h_macros() -------------- ***\n\n");
    109 
    110     printUString("iterate forward through: ", input, LENGTHOF(input));
    111     for(i=0; i<LENGTHOF(input); /* U16_NEXT post-increments */) {
    112         /* Iterating forwards
    113            Codepoint at offset 0: U+0061
    114            Codepoint at offset 1: U+10000
    115            Codepoint at offset 3: U+10ffff
    116            Codepoint at offset 5: U+0062
    117         */
    118         printf("Codepoint at offset %d: U+", i);
    119         U16_NEXT(input, i, LENGTHOF(input), c);
    120         printf("%04x\n", c);
    121     }
    122 
    123     puts("");
    124 
    125     isError=FALSE;
    126     i=1; /* write position, gets post-incremented so needs to be in an l-value */
    127     U16_APPEND(input, i, LENGTHOF(input), 0x0062, isError);
    128 
    129     printUString("iterate backward through: ", input, LENGTHOF(input));
    130     for(i=LENGTHOF(input); i>0; /* U16_PREV pre-decrements */) {
    131         U16_PREV(input, 0, i, c);
    132         /* Iterating backwards
    133            Codepoint at offset 5: U+0062
    134            Codepoint at offset 3: U+10ffff
    135            Codepoint at offset 2: U+dc00 -- unpaired surrogate because lead surr. overwritten
    136            Codepoint at offset 1: U+0062 -- by this BMP code point
    137            Codepoint at offset 0: U+0061
    138         */
    139         printf("Codepoint at offset %d: U+%04x\n", i, c);
    140     }
    141 }
    142 
    143 // sample code for Unicode strings in C ------------------------------------ ***
    144 
    145 static void demo_C_Unicode_strings() {
    146     printf("\n* demo_C_Unicode_strings() --------- ***\n\n");
    147 
    148     static const UChar text[]={ 0x41, 0x42, 0x43, 0 };          /* "ABC" */
    149     static const UChar appendText[]={ 0x61, 0x62, 0x63, 0 };    /* "abc" */
    150     static const UChar cmpText[]={ 0x61, 0x53, 0x73, 0x43, 0 }; /* "aSsC" */
    151     UChar buffer[32];
    152     int32_t compare;
    153     int32_t length=u_strlen(text); /* length=3 */
    154 
    155     /* simple ANSI C-style functions */
    156     buffer[0]=0;                    /* empty, NUL-terminated string */
    157     u_strncat(buffer, text, 1);     /* append just n=1 character ('A') */
    158     u_strcat(buffer, appendText);   /* buffer=="Aabc" */
    159     length=u_strlen(buffer);        /* length=4 */
    160     printUString("should be \"Aabc\": ", buffer, -1);
    161 
    162     /* bitwise comparing buffer with text */
    163     compare=u_strcmp(buffer, text);
    164     if(compare<=0) {
    165         printf("String comparison error, expected \"Aabc\" > \"ABC\"\n");
    166     }
    167 
    168     /* Build "A<sharp s>C" in the buffer... */
    169     u_strcpy(buffer, text);
    170     buffer[1]=0xdf; /* sharp s, case-compares equal to "ss" */
    171     printUString("should be \"A<sharp s>C\": ", buffer, -1);
    172 
    173     /* Compare two strings case-insensitively using full case folding */
    174     compare=u_strcasecmp(buffer, cmpText, U_FOLD_CASE_DEFAULT);
    175     if(compare!=0) {
    176         printf("String case insensitive comparison error, expected \"AbC\" to be equal to \"ABC\"\n");
    177     }
    178 }
    179 
    180 // sample code for case mappings with C APIs -------------------------------- ***
    181 
    182 static void demoCaseMapInC() {
    183     /*
    184      * input=
    185      *   "aB<capital sigma>"
    186      *   "iI<small dotless i><capital dotted I> "
    187      *   "<sharp s> <small lig. ffi>"
    188      *   "<small final sigma><small sigma><capital sigma>"
    189      */
    190     static const UChar input[]={
    191         0x61, 0x42, 0x3a3,
    192         0x69, 0x49, 0x131, 0x130, 0x20,
    193         0xdf, 0x20, 0xfb03,
    194         0x3c2, 0x3c3, 0x3a3, 0
    195     };
    196     UChar buffer[32];
    197 
    198     UErrorCode errorCode;
    199     UChar32 c;
    200     int32_t i, j, length;
    201     UBool isError;
    202 
    203     printf("\n* demoCaseMapInC() ----------------- ***\n\n");
    204 
    205     /*
    206      * First, use simple case mapping functions which provide
    207      * 1:1 code point mappings without context/locale ID.
    208      *
    209      * Note that some mappings will not be "right" because some "real"
    210      * case mappings require context, depend on the locale ID,
    211      * and/or result in a change in the number of code points.
    212      */
    213     printUString("input string: ", input, -1);
    214 
    215     /* uppercase */
    216     isError=FALSE;
    217     for(i=j=0; j<LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
    218         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
    219         if(c==0) {
    220             break; /* stop at terminating NUL, no need to terminate buffer */
    221         }
    222         c=u_toupper(c);
    223         U16_APPEND(buffer, j, LENGTHOF(buffer), c, isError);
    224     }
    225     printUString("simple-uppercased: ", buffer, j);
    226     /* lowercase */
    227     isError=FALSE;
    228     for(i=j=0; j<LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
    229         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
    230         if(c==0) {
    231             break; /* stop at terminating NUL, no need to terminate buffer */
    232         }
    233         c=u_tolower(c);
    234         U16_APPEND(buffer, j, LENGTHOF(buffer), c, isError);
    235     }
    236     printUString("simple-lowercased: ", buffer, j);
    237     /* titlecase */
    238     isError=FALSE;
    239     for(i=j=0; j<LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
    240         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
    241         if(c==0) {
    242             break; /* stop at terminating NUL, no need to terminate buffer */
    243         }
    244         c=u_totitle(c);
    245         U16_APPEND(buffer, j, LENGTHOF(buffer), c, isError);
    246     }
    247     printUString("simple-titlecased: ", buffer, j);
    248     /* case-fold/default */
    249     isError=FALSE;
    250     for(i=j=0; j<LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
    251         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
    252         if(c==0) {
    253             break; /* stop at terminating NUL, no need to terminate buffer */
    254         }
    255         c=u_foldCase(c, U_FOLD_CASE_DEFAULT);
    256         U16_APPEND(buffer, j, LENGTHOF(buffer), c, isError);
    257     }
    258     printUString("simple-case-folded/default: ", buffer, j);
    259     /* case-fold/Turkic */
    260     isError=FALSE;
    261     for(i=j=0; j<LENGTHOF(buffer) && !isError; /* U16_NEXT post-increments */) {
    262         U16_NEXT(input, i, INT32_MAX, c); /* without length because NUL-terminated */
    263         if(c==0) {
    264             break; /* stop at terminating NUL, no need to terminate buffer */
    265         }
    266         c=u_foldCase(c, U_FOLD_CASE_EXCLUDE_SPECIAL_I);
    267         U16_APPEND(buffer, j, LENGTHOF(buffer), c, isError);
    268     }
    269     printUString("simple-case-folded/Turkic: ", buffer, j);
    270 
    271     /*
    272      * Second, use full case mapping functions which provide
    273      * 1:n code point mappings (n can be 0!) and are sensitive to context and locale ID.
    274      *
    275      * Note that lower/upper/titlecasing take a locale ID while case-folding
    276      * has bit flag options instead, by design of the Unicode SpecialCasing.txt UCD file.
    277      *
    278      * Also, string titlecasing requires a BreakIterator to find starts of words.
    279      * The sample code here passes in a NULL pointer; u_strToTitle() will open and close a default
    280      * titlecasing BreakIterator automatically.
    281      * For production code where many strings are titlecased it would be more efficient
    282      * to open a BreakIterator externally and pass it in.
    283      */
    284     printUString("\ninput string: ", input, -1);
    285 
    286     /* lowercase/English */
    287     errorCode=U_ZERO_ERROR;
    288     length=u_strToLower(buffer, LENGTHOF(buffer), input, -1, "en", &errorCode);
    289     if(U_SUCCESS(errorCode)) {
    290         printUString("full-lowercased/en: ", buffer, length);
    291     } else {
    292         printf("error in u_strToLower(en)=%ld error=%s\n", length, u_errorName(errorCode));
    293     }
    294     /* lowercase/Turkish */
    295     errorCode=U_ZERO_ERROR;
    296     length=u_strToLower(buffer, LENGTHOF(buffer), input, -1, "tr", &errorCode);
    297     if(U_SUCCESS(errorCode)) {
    298         printUString("full-lowercased/tr: ", buffer, length);
    299     } else {
    300         printf("error in u_strToLower(tr)=%ld error=%s\n", length, u_errorName(errorCode));
    301     }
    302     /* uppercase/English */
    303     errorCode=U_ZERO_ERROR;
    304     length=u_strToUpper(buffer, LENGTHOF(buffer), input, -1, "en", &errorCode);
    305     if(U_SUCCESS(errorCode)) {
    306         printUString("full-uppercased/en: ", buffer, length);
    307     } else {
    308         printf("error in u_strToUpper(en)=%ld error=%s\n", length, u_errorName(errorCode));
    309     }
    310     /* uppercase/Turkish */
    311     errorCode=U_ZERO_ERROR;
    312     length=u_strToUpper(buffer, LENGTHOF(buffer), input, -1, "tr", &errorCode);
    313     if(U_SUCCESS(errorCode)) {
    314         printUString("full-uppercased/tr: ", buffer, length);
    315     } else {
    316         printf("error in u_strToUpper(tr)=%ld error=%s\n", length, u_errorName(errorCode));
    317     }
    318     /* titlecase/English */
    319     errorCode=U_ZERO_ERROR;
    320     length=u_strToTitle(buffer, LENGTHOF(buffer), input, -1, NULL, "en", &errorCode);
    321     if(U_SUCCESS(errorCode)) {
    322         printUString("full-titlecased/en: ", buffer, length);
    323     } else {
    324         printf("error in u_strToTitle(en)=%ld error=%s\n", length, u_errorName(errorCode));
    325     }
    326     /* titlecase/Turkish */
    327     errorCode=U_ZERO_ERROR;
    328     length=u_strToTitle(buffer, LENGTHOF(buffer), input, -1, NULL, "tr", &errorCode);
    329     if(U_SUCCESS(errorCode)) {
    330         printUString("full-titlecased/tr: ", buffer, length);
    331     } else {
    332         printf("error in u_strToTitle(tr)=%ld error=%s\n", length, u_errorName(errorCode));
    333     }
    334     /* case-fold/default */
    335     errorCode=U_ZERO_ERROR;
    336     length=u_strFoldCase(buffer, LENGTHOF(buffer), input, -1, U_FOLD_CASE_DEFAULT, &errorCode);
    337     if(U_SUCCESS(errorCode)) {
    338         printUString("full-case-folded/default: ", buffer, length);
    339     } else {
    340         printf("error in u_strFoldCase(default)=%ld error=%s\n", length, u_errorName(errorCode));
    341     }
    342     /* case-fold/Turkic */
    343     errorCode=U_ZERO_ERROR;
    344     length=u_strFoldCase(buffer, LENGTHOF(buffer), input, -1, U_FOLD_CASE_EXCLUDE_SPECIAL_I, &errorCode);
    345     if(U_SUCCESS(errorCode)) {
    346         printUString("full-case-folded/Turkic: ", buffer, length);
    347     } else {
    348         printf("error in u_strFoldCase(Turkic)=%ld error=%s\n", length, u_errorName(errorCode));
    349     }
    350 }
    351 
    352 // sample code for case mappings with C++ APIs ------------------------------ ***
    353 
    354 static void demoCaseMapInCPlusPlus() {
    355     /*
    356      * input=
    357      *   "aB<capital sigma>"
    358      *   "iI<small dotless i><capital dotted I> "
    359      *   "<sharp s> <small lig. ffi>"
    360      *   "<small final sigma><small sigma><capital sigma>"
    361      */
    362     static const UChar input[]={
    363         0x61, 0x42, 0x3a3,
    364         0x69, 0x49, 0x131, 0x130, 0x20,
    365         0xdf, 0x20, 0xfb03,
    366         0x3c2, 0x3c3, 0x3a3, 0
    367     };
    368 
    369     printf("\n* demoCaseMapInCPlusPlus() --------- ***\n\n");
    370 
    371     UnicodeString s(input), t;
    372     const Locale &en=Locale::getEnglish();
    373     Locale tr("tr");
    374 
    375     /*
    376      * Full case mappings as in demoCaseMapInC(), using UnicodeString functions.
    377      * These functions modify the string object itself.
    378      * Since we want to keep the input string around, we copy it each time
    379      * and case-map the copy.
    380      */
    381     printUnicodeString("input string: ", s);
    382 
    383     /* lowercase/English */
    384     printUnicodeString("full-lowercased/en: ", (t=s).toLower(en));
    385     /* lowercase/Turkish */
    386     printUnicodeString("full-lowercased/tr: ", (t=s).toLower(tr));
    387     /* uppercase/English */
    388     printUnicodeString("full-uppercased/en: ", (t=s).toUpper(en));
    389     /* uppercase/Turkish */
    390     printUnicodeString("full-uppercased/tr: ", (t=s).toUpper(tr));
    391     /* titlecase/English */
    392     printUnicodeString("full-titlecased/en: ", (t=s).toTitle(NULL, en));
    393     /* titlecase/Turkish */
    394     printUnicodeString("full-titlecased/tr: ", (t=s).toTitle(NULL, tr));
    395     /* case-folde/default */
    396     printUnicodeString("full-case-folded/default: ", (t=s).foldCase(U_FOLD_CASE_DEFAULT));
    397     /* case-folde/Turkic */
    398     printUnicodeString("full-case-folded/Turkic: ", (t=s).foldCase(U_FOLD_CASE_EXCLUDE_SPECIAL_I));
    399 }
    400 
    401 // sample code for UnicodeString storage models ----------------------------- ***
    402 
    403 static const UChar readonly[]={
    404     0x61, 0x31, 0x20ac
    405 };
    406 static UChar writeable[]={
    407     0x62, 0x32, 0xdbc0, 0xdc01 // includes a surrogate pair for a supplementary code point
    408 };
    409 static char out[100];
    410 
    411 static void
    412 demoUnicodeStringStorage() {
    413     // These sample code lines illustrate how to use UnicodeString, and the
    414     // comments tell what happens internally. There are no APIs to observe
    415     // most of this programmatically, except for stepping into the code
    416     // with a debugger.
    417     // This is by design to hide such details from the user.
    418     int32_t i;
    419 
    420     printf("\n* demoUnicodeStringStorage() ------- ***\n\n");
    421 
    422     // * UnicodeString with internally stored contents
    423     // instantiate a UnicodeString from a single code point
    424     // the few (2) UChars will be stored in the object itself
    425     UnicodeString one((UChar32)0x24001);
    426     // this copies the few UChars into the "two" object
    427     UnicodeString two=one;
    428     printf("length of short string copy: %d\n", two.length());
    429     // set "one" to contain the 3 UChars from readonly
    430     // this setTo() variant copies the characters
    431     one.setTo(readonly, LENGTHOF(readonly));
    432 
    433     // * UnicodeString with allocated contents
    434     // build a longer string that will not fit into the object's buffer
    435     one+=UnicodeString(writeable, LENGTHOF(writeable));
    436     one+=one;
    437     one+=one;
    438     printf("length of longer string: %d\n", one.length());
    439     // copying will use the same allocated buffer and increment the reference
    440     // counter
    441     two=one;
    442     printf("length of longer string copy: %d\n", two.length());
    443 
    444     // * UnicodeString using readonly-alias to a const UChar array
    445     // construct a string that aliases a readonly buffer
    446     UnicodeString three(FALSE, readonly, LENGTHOF(readonly));
    447     printUnicodeString("readonly-alias string: ", three);
    448     // copy-on-write: any modification to the string results in
    449     // a copy to either the internal buffer or to a newly allocated one
    450     three.setCharAt(1, 0x39);
    451     printUnicodeString("readonly-aliasing string after modification: ", three);
    452     // the aliased array is not modified
    453     for(i=0; i<three.length(); ++i) {
    454         printf("readonly buffer[%d] after modifying its string: 0x%lx\n",
    455                i, readonly[i]);
    456     }
    457     // setTo() readonly alias
    458     one.setTo(FALSE, writeable, LENGTHOF(writeable));
    459     // copying the readonly-alias object with fastCopyFrom() (new in ICU 2.4)
    460     // will readonly-alias the same buffer
    461     two.fastCopyFrom(one);
    462     printUnicodeString("fastCopyFrom(readonly alias of \"writeable\" array): ", two);
    463     printf("verify that a fastCopyFrom(readonly alias) uses the same buffer pointer: %d (should be 1)\n",
    464         one.getBuffer()==two.getBuffer());
    465     // a normal assignment will clone the contents (new in ICU 2.4)
    466     two=one;
    467     printf("verify that a regular copy of a readonly alias uses a different buffer pointer: %d (should be 0)\n",
    468         one.getBuffer()==two.getBuffer());
    469 
    470     // * UnicodeString using writeable-alias to a non-const UChar array
    471     UnicodeString four(writeable, LENGTHOF(writeable), LENGTHOF(writeable));
    472     printUnicodeString("writeable-alias string: ", four);
    473     // a modification writes through to the buffer
    474     four.setCharAt(1, 0x39);
    475     for(i=0; i<four.length(); ++i) {
    476         printf("writeable-alias backing buffer[%d]=0x%lx "
    477                "after modification\n", i, writeable[i]);
    478     }
    479     // a copy will not alias any more;
    480     // instead, it will get a copy of the contents into allocated memory
    481     two=four;
    482     two.setCharAt(1, 0x21);
    483     for(i=0; i<two.length(); ++i) {
    484         printf("writeable-alias backing buffer[%d]=0x%lx after "
    485                "modification of string copy\n", i, writeable[i]);
    486     }
    487     // setTo() writeable alias, capacity==length
    488     one.setTo(writeable, LENGTHOF(writeable), LENGTHOF(writeable));
    489     // grow the string - it will not fit into the backing buffer any more
    490     // and will get copied before modification
    491     one.append((UChar)0x40);
    492     // shrink it back so it would fit
    493     one.truncate(one.length()-1);
    494     // we still operate on the copy
    495     one.setCharAt(1, 0x25);
    496     printf("string after growing too much and then shrinking[1]=0x%lx\n"
    497            "                          backing store for this[1]=0x%lx\n",
    498            one.charAt(1), writeable[1]);
    499     // if we need it in the original buffer, then extract() to it
    500     // extract() does not do anything if the string aliases that same buffer
    501     // i=min(one.length(), length of array)
    502     if(one.length()<LENGTHOF(writeable)) {
    503         i=one.length();
    504     } else {
    505         i=LENGTHOF(writeable);
    506     }
    507     one.extract(0, i, writeable);
    508     for(i=0; i<LENGTHOF(writeable); ++i) {
    509         printf("writeable-alias backing buffer[%d]=0x%lx after re-extract\n",
    510                i, writeable[i]);
    511     }
    512 }
    513 
    514 // sample code for UnicodeString instantiations ----------------------------- ***
    515 
    516 static void
    517 demoUnicodeStringInit() {
    518     // *** Make sure to read about invariant characters in utypes.h! ***
    519     // Initialization of Unicode strings from C literals works _only_ for
    520     // invariant characters!
    521 
    522     printf("\n* demoUnicodeStringInit() ---------- ***\n\n");
    523 
    524     // the string literal is 32 chars long - this must be counted for the macro
    525     UnicodeString invariantOnly=UNICODE_STRING("such characters are safe 123 %-.", 32);
    526 
    527     /*
    528      * In C, we need two macros: one to declare the UChar[] array, and
    529      * one to populate it; the second one is a noop on platforms where
    530      * wchar_t is compatible with UChar and ASCII-based.
    531      * The length of the string literal must be counted for both macros.
    532      */
    533     /* declare the invString array for the string */
    534     U_STRING_DECL(invString, "such characters are safe 123 %-.", 32);
    535     /* populate it with the characters */
    536     U_STRING_INIT(invString, "such characters are safe 123 %-.", 32);
    537 
    538     // compare the C and C++ strings
    539     printf("C and C++ Unicode strings are equal: %d\n", invariantOnly==UnicodeString(TRUE, invString, 32));
    540 
    541     /*
    542      * convert between char * and UChar * strings that
    543      * contain only invariant characters
    544      */
    545     static const char *cs1="such characters are safe 123 %-.";
    546     static UChar us1[40];
    547     static char cs2[40];
    548     u_charsToUChars(cs1, us1, 33); /* include the terminating NUL */
    549     u_UCharsToChars(us1, cs2, 33);
    550     printf("char * -> UChar * -> char * with only "
    551            "invariant characters: \"%s\"\n",
    552            cs2);
    553 
    554     // initialize a UnicodeString from a string literal that contains
    555     // escape sequences written with invariant characters
    556     // do not forget to duplicate the backslashes for ICU to see them
    557     // then, count each double backslash only once!
    558     UnicodeString german=UNICODE_STRING(
    559         "Sch\\u00f6nes Auto: \\u20ac 11240.\\fPrivates Zeichen: \\U00102345\\n", 64).
    560         unescape();
    561     printUnicodeString("german UnicodeString from unescaping:\n    ", german);
    562 
    563     /*
    564      * C: convert and unescape a char * string with only invariant
    565      * characters to fill a UChar * string
    566      */
    567     UChar buffer[200];
    568     int32_t length;
    569     length=u_unescape(
    570         "Sch\\u00f6nes Auto: \\u20ac 11240.\\fPrivates Zeichen: \\U00102345\\n",
    571         buffer, LENGTHOF(buffer));
    572     printf("german C Unicode string from char * unescaping: (length %d)\n    ", length);
    573     printUnicodeString("", UnicodeString(buffer));
    574 }
    575 
    576 extern int
    577 main(int argc, const char *argv[]) {
    578     UErrorCode errorCode=U_ZERO_ERROR;
    579 
    580     // Note: Using a global variable for any object is not exactly thread-safe...
    581 
    582     // You can change this call to e.g. ucnv_open("UTF-8", &errorCode) if you pipe
    583     // the output to a file and look at it with a Unicode-capable editor.
    584     // This will currently affect only the printUString() function, see the code above.
    585     // printUnicodeString() could use this, too, by changing to an extract() overload
    586     // that takes a UConverter argument.
    587     cnv=ucnv_open(NULL, &errorCode);
    588     if(U_FAILURE(errorCode)) {
    589         fprintf(stderr, "error %s opening the default converter\n", u_errorName(errorCode));
    590         return errorCode;
    591     }
    592 
    593     ucnv_setFromUCallBack(cnv, UCNV_FROM_U_CALLBACK_ESCAPE, UCNV_ESCAPE_C, NULL, NULL, &errorCode);
    594     if(U_FAILURE(errorCode)) {
    595         fprintf(stderr, "error %s setting the escape callback in the default converter\n", u_errorName(errorCode));
    596         ucnv_close(cnv);
    597         return errorCode;
    598     }
    599 
    600     demo_utf_h_macros();
    601     demo_C_Unicode_strings();
    602     demoCaseMapInC();
    603     demoCaseMapInCPlusPlus();
    604     demoUnicodeStringStorage();
    605     demoUnicodeStringInit();
    606 
    607     ucnv_close(cnv);
    608     return 0;
    609 }
    610