219 lines
7.8 KiB
C++
219 lines
7.8 KiB
C++
/*
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*******************************************************************************
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*
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* Copyright (C) 2000, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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*******************************************************************************
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* file name: ustring.c
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* encoding: US-ASCII
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* tab size: 8 (not used)
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* indentation:4
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*
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* created on: 2000aug15
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* created by: Markus W. Scherer
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*
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* This file contains sample code that illustrates the use of Unicode strings
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* with ICU.
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*/
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#include <stdio.h>
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#include "unicode/utypes.h"
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#include "unicode/ustring.h"
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#include "unicode/unistr.h"
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// helper function --------------------------------------------------------- ***
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static void
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printUnicodeString(const UnicodeString &s) {
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static char out[200];
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int32_t i, length;
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// output the string, converted to the platform encoding
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out[s.extract(0, 99, out)]=0;
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printf("%s {", out);
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// output the code units
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length=s.length();
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for(i=0; i<length; ++i) {
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printf(" %04x", s.charAt(i));
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}
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printf(" }\n");
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}
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// sample code for storage models ------------------------------------------ ***
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#define LENGTHOF(array) (sizeof(array)/sizeof((array)[0]))
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static const UChar readonly[]={
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0x61, 0x31, 0x20ac
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};
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static UChar writeable[]={
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0x62, 0x32, 0xdbc0, 0xdc01
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};
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static char out[100];
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static void
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demoStorage() {
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// These sample code lines illustrate how to use UnicodeString, and the
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// comments tell what happens internally. There are no APIs to observe
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// most of this programmatically, except for stepping into the code
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// with a debugger.
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// This is by design to hide such details from the user.
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// * UnicodeString with internally stored contents
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// instantiate a UnicodeString from a single code point
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// the few (2) UChars will be stored in the object itself
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UnicodeString one((UChar32)0x24001);
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// this copies the few UChars into the "two" object
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UnicodeString two=one;
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printf("length of short string copy: %d\n", two.length());
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// set "one" to contain the 3 UChars from readonly
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one.setTo(readonly, LENGTHOF(readonly));
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// * UnicodeString with allocated contents
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// build a longer string that will not fit into the object's buffer
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one+=UnicodeString(writeable, LENGTHOF(writeable));
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one+=one;
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one+=one;
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printf("length of longer string: %d\n", one.length());
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// copying will use the same allocated buffer and increment the reference
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// counter
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two=one;
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printf("length of longer string copy: %d\n", two.length());
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// * UnicodeString using readonly-alias to a const UChar array
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// construct a string that aliases a readonly buffer
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UnicodeString three(FALSE, readonly, LENGTHOF(readonly));
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int32_t i;
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for(i=0; i<three.length(); ++i) {
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printf("readonly-alias string[%d]=0x%lx\n", i, three.charAt(i));
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}
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// copy-on-write: any modification to the string results in
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// a copy to either the internal buffer or to a newly allocated one
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three.setCharAt(1, 0x39);
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out[three.extract(0, 99, out)]=0;
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printf("readonly-aliasing string after modification: %s\n", out);
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// the aliased array is not modified
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for(i=0; i<three.length(); ++i) {
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printf("readonly buffer[%d] after modifying its string: 0x%lx\n",
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i, readonly[i]);
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}
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// setTo() readonly alias
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one.setTo(FALSE, writeable, LENGTHOF(writeable));
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// copying the readonly-alias object will readonly-alias the same buffer
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two=one;
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out[two.extract(0, 99, out)]=0;
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printf("copy of readonly-alias string of \"writeable\" array: %s\n", out);
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// * UnicodeString using writeable-alias to a non-const UChar array
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UnicodeString four(writeable, LENGTHOF(writeable), LENGTHOF(writeable));
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for(i=0; i<four.length(); ++i) {
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printf("writeable-alias string[%d]=0x%lx\n", i, four.charAt(i));
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}
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// a modification writes through to the buffer
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four.setCharAt(1, 0x39);
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for(i=0; i<four.length(); ++i) {
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printf("writeable-alias backing buffer[%d]=0x%lx "
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"after modification\n", i, writeable[i]);
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}
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// a copy will not alias any more;
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// instead, it will get a copy of the contents into allocated memory
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two=four;
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two.setCharAt(1, 0x21);
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for(i=0; i<two.length(); ++i) {
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printf("writeable-alias backing buffer[%d]=0x%lx after "
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"modification of string copy\n", i, writeable[i]);
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}
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// setTo() writeable alias
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one.setTo(writeable, LENGTHOF(writeable), LENGTHOF(writeable));
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// grow the string - it will not fit into the backing buffer any more
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// and will get copied before modification
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one.append((UChar)0x40);
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// shrink it back so it would fit
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one.truncate(one.length()-1);
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// we still operate on the copy
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one.setCharAt(1, 0x25);
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printf("string after growing too much and then shrinking[1]=0x%lx\n"
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" backing store for this[1]=0x%lx\n",
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one.charAt(1), writeable[1]);
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// if we need it in the original buffer, then extract() to it
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// extract() does not do anything if the string aliases that same buffer
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// i=min(one.length(), length of array)
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if(one.length()<LENGTHOF(writeable)) {
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i=one.length();
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} else {
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i=LENGTHOF(writeable);
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}
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one.extract(0, i, writeable);
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for(i=0; i<LENGTHOF(writeable); ++i) {
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printf("writeable-alias backing buffer[%d]=0x%lx after re-extract\n",
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i, writeable[i]);
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}
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}
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// sample code for instantiating Unicode strings --------------------------- ***
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static void
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initString() {
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// the string literal is 32 chars long - this must be counted for the macro
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UnicodeString invariantOnly=UNICODE_STRING("such characters are safe 123 %-.", 32);
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/*
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* In C, we need two macros: one to declare the UChar[] array, and
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* one to populate it; the second one is a noop on platforms where
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* wchar_t is compatible with UChar and ASCII-based.
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* The length of the string literal must be counted for both macros.
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*/
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/* declare the invString array for the string */
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U_STRING_DECL(invString, "such characters are safe 123 %-.", 32);
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/* populate it with the characters */
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U_STRING_INIT(invString, "such characters are safe 123 %-.", 32);
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// compare the C and C++ strings
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printf("C and C++ Unicode strings are equal: %d\n", invariantOnly==UnicodeString(TRUE, invString, 32));
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/*
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* convert between char * and UChar * strings that
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* contain only invariant characters
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*/
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static const char *cs1="such characters are safe 123 %-.";
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static UChar us1[40];
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static char cs2[40];
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u_charsToUChars(cs1, us1, 33); /* include the terminating NUL */
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u_UCharsToChars(us1, cs2, 33);
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printf("char * -> UChar * -> char * with only "
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"invariant characters: \"%s\"\n",
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cs2);
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// initialize a UnicodeString from a string literal that contains
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// escape sequences written with invariant characters
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// do not forget to duplicate the backslashes for ICU to see them
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// then, count each double backslash only once!
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UnicodeString german=UNICODE_STRING(
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"Sch\\u00f6nes Auto: \\u20ac 11240.\\fPrivates Zeichen: \\U00102345\\n", 64).
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unescape();
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printf("german UnicodeString from unescaping:\n ");
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printUnicodeString(german);
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/*
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* C: convert and unescape a char * string with only invariant
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* characters to fill a UChar * string
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*/
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UChar buffer[200];
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int32_t length;
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length=u_unescape(
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"Sch\\u00f6nes Auto: \\u20ac 11240.\\fPrivates Zeichen: \\U00102345\\n",
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buffer, LENGTHOF(buffer));
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printf("german C Unicode string from char * unescaping: (length %d)\n ", length);
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printUnicodeString(UnicodeString(buffer));
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}
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extern int
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main(int argc, const char *argv[]) {
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demoStorage();
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initString();
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return 0;
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}
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