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