最近在做一套跨平臺的簡訊收發開發程式，遇到了一個問題，那就是文字編碼轉換。在windowsg下的轉換有庫函式

MultiByteToWideChar        WideCharToMultiByte,這二個，但是我要的是在linux機器下也可以正常使用，所以google了一天，發現了二個解決方案，一個是libiconv,一個就是ICU了，實際使用後，發現還是ICU更好用，下面是一個簡單的例子。

#include <unicode/ucnv.h> #ifdef _WIN32 #pragma comment(lib, "icuuc.lib") #endif //返回0為成功，錯誤程式碼定義見後面 int convert(const char * toConverterName, const char * fromConverterName, char * target, int32_t targetCapacity, const char * source, int32_t sourceLength) { UErrorCode error = U_ZERO_ERROR; ucnv_convert(toConverterName,fromConverterName,target, targetCapacity, source, sourceLength, &error ); return error; } int _tmain(int argc, _TCHAR* argv[]) { wchar_t aaa[] = L"中國人的系統上123323"; int alen = wcslen(aaa); int blen=alen*2+sizeof(int); char *abuff=new char[blen]; int result = convert( "gb2312", "utf-16le", abuff, blen, (const char *)aaa, alen); cout << abuff << endl<<strlen(abuff)<<endl; delete []abuff; return 0; }

typedef enum UErrorCode { /* The ordering of U_ERROR_INFO_START Vs U_USING_FALLBACK_WARNING looks weird * and is that way because VC++ debugger displays first encountered constant, * which is not the what the code is used for */ U_USING_FALLBACK_WARNING = -128, /**< A resource bundle lookup returned a fallback result (not an error) */ U_ERROR_WARNING_START = -128, /**< Start of information results (semantically successful) */ U_USING_DEFAULT_WARNING = -127, /**< A resource bundle lookup returned a result from the root locale (not an error) */ U_SAFECLONE_ALLOCATED_WARNING = -126, /**< A SafeClone operation required allocating memory (informational only) */ U_STATE_OLD_WARNING = -125, /**< ICU has to use compatibility layer to construct the service. Expect performance/memory usage degradation. Consider upgrading */ U_STRING_NOT_TERMINATED_WARNING = -124,/**< An output string could not be NUL-terminated because output length==destCapacity. */ U_SORT_KEY_TOO_SHORT_WARNING = -123, /**< Number of levels requested in getBound is higher than the number of levels in the sort key */ U_AMBIGUOUS_ALIAS_WARNING = -122, /**< This converter alias can go to different converter implementations */ U_DIFFERENT_UCA_VERSION = -121, /**< ucol_open encountered a mismatch between UCA version and collator image version, so the collator was constructed from rules. No impact to further function */ U_PLUGIN_CHANGED_LEVEL_WARNING = -120, /**< A plugin caused a level change. May not be an error, but later plugins may not load. */ U_ERROR_WARNING_LIMIT, /**< This must always be the last warning value to indicate the limit for UErrorCode warnings (last warning code +1) */ U_ZERO_ERROR = 0, /**< No error, no warning. */ U_ILLEGAL_ARGUMENT_ERROR = 1, /**< Start of codes indicating failure */ U_MISSING_RESOURCE_ERROR = 2, /**< The requested resource cannot be found */ U_INVALID_FORMAT_ERROR = 3, /**< Data format is not what is expected */ U_FILE_ACCESS_ERROR = 4, /**< The requested file cannot be found */ U_INTERNAL_PROGRAM_ERROR = 5, /**< Indicates a bug in the library code */ U_MESSAGE_PARSE_ERROR = 6, /**< Unable to parse a message (message format) */ U_MEMORY_ALLOCATION_ERROR = 7, /**< Memory allocation error */ U_INDEX_OUTOFBOUNDS_ERROR = 8, /**< Trying to access the index that is out of bounds */ U_PARSE_ERROR = 9, /**< Equivalent to Java ParseException */ U_INVALID_CHAR_FOUND = 10, /**< Character conversion: Unmappable input sequence. In other APIs: Invalid character. */ U_TRUNCATED_CHAR_FOUND = 11, /**< Character conversion: Incomplete input sequence. */ U_ILLEGAL_CHAR_FOUND = 12, /**< Character conversion: Illegal input sequence/combination of input units. */ U_INVALID_TABLE_FORMAT = 13, /**< Conversion table file found, but corrupted */ U_INVALID_TABLE_FILE = 14, /**< Conversion table file not found */ U_BUFFER_OVERFLOW_ERROR = 15, /**< A result would not fit in the supplied buffer */ U_UNSUPPORTED_ERROR = 16, /**< Requested operation not supported in current context */ U_RESOURCE_TYPE_MISMATCH = 17, /**< an operation is requested over a resource that does not support it */ U_ILLEGAL_ESCAPE_SEQUENCE = 18, /**< ISO-2022 illlegal escape sequence */ U_UNSUPPORTED_ESCAPE_SEQUENCE = 19, /**< ISO-2022 unsupported escape sequence */ U_NO_SPACE_AVAILABLE = 20, /**< No space available for in-buffer expansion for Arabic shaping */ U_CE_NOT_FOUND_ERROR = 21, /**< Currently used only while setting variable top, but can be used generally */ U_PRIMARY_TOO_LONG_ERROR = 22, /**< User tried to set variable top to a primary that is longer than two bytes */ U_STATE_TOO_OLD_ERROR = 23, /**< ICU cannot construct a service from this state, as it is no longer supported */ U_TOO_MANY_ALIASES_ERROR = 24, /**< There are too many aliases in the path to the requested resource. It is very possible that a circular alias definition has occured */ U_ENUM_OUT_OF_SYNC_ERROR = 25, /**< UEnumeration out of sync with underlying collection */ U_INVARIANT_CONVERSION_ERROR = 26, /**< Unable to convert a UChar* string to char* with the invariant converter. */ U_INVALID_STATE_ERROR = 27, /**< Requested operation can not be completed with ICU in its current state */ U_COLLATOR_VERSION_MISMATCH = 28, /**< Collator version is not compatible with the base version */ U_USELESS_COLLATOR_ERROR = 29, /**< Collator is options only and no base is specified */ U_NO_WRITE_PERMISSION = 30, /**< Attempt to modify read-only or constant data. */ U_STANDARD_ERROR_LIMIT, /**< This must always be the last value to indicate the limit for standard errors */ /* * the error code range 0x10000 0x10100 are reserved for Transliterator */ U_BAD_VARIABLE_DEFINITION=0x10000,/**< Missing '</p> or duplicate variable name */ U_PARSE_ERROR_START = 0x10000, /**< Start of Transliterator errors */ U_MALFORMED_RULE, /**< Elements of a rule are misplaced */ U_MALFORMED_SET, /**< A UnicodeSet pattern is invalid*/ U_MALFORMED_SYMBOL_REFERENCE, /**< UNUSED as of ICU 2.4 */ U_MALFORMED_UNICODE_ESCAPE, /**< A Unicode escape pattern is invalid*/ U_MALFORMED_VARIABLE_DEFINITION, /**< A variable definition is invalid */ U_MALFORMED_VARIABLE_REFERENCE, /**< A variable reference is invalid */ U_MISMATCHED_SEGMENT_DELIMITERS, /**< UNUSED as of ICU 2.4 */ U_MISPLACED_ANCHOR_START, /**< A start anchor appears at an illegal position */ U_MISPLACED_CURSOR_OFFSET, /**< A cursor offset occurs at an illegal position */ U_MISPLACED_QUANTIFIER, /**< A quantifier appears after a segment close delimiter */ U_MISSING_OPERATOR, /**< A rule contains no operator */ U_MISSING_SEGMENT_CLOSE, /**< UNUSED as of ICU 2.4 */ U_MULTIPLE_ANTE_CONTEXTS, /**< More than one ante context */ U_MULTIPLE_CURSORS, /**< More than one cursor */ U_MULTIPLE_POST_CONTEXTS, /**< More than one post context */ U_TRAILING_BACKSLASH, /**< A dangling backslash */ U_UNDEFINED_SEGMENT_REFERENCE, /**< A segment reference does not correspond to a defined segment */ U_UNDEFINED_VARIABLE, /**< A variable reference does not correspond to a defined variable */ U_UNQUOTED_SPECIAL, /**< A special character was not quoted or escaped */ U_UNTERMINATED_QUOTE, /**< A closing single quote is missing */ U_RULE_MASK_ERROR, /**< A rule is hidden by an earlier more general rule */ U_MISPLACED_COMPOUND_FILTER, /**< A compound filter is in an invalid location */ U_MULTIPLE_COMPOUND_FILTERS, /**< More than one compound filter */ U_INVALID_RBT_SYNTAX, /**< A "::id" rule was passed to the RuleBasedTransliterator parser */ U_INVALID_PROPERTY_PATTERN, /**< UNUSED as of ICU 2.4 */ U_MALFORMED_PRAGMA, /**< A 'use' pragma is invlalid */ U_UNCLOSED_SEGMENT, /**< A closing ')' is missing */ U_ILLEGAL_CHAR_IN_SEGMENT, /**< UNUSED as of ICU 2.4 */ U_VARIABLE_RANGE_EXHAUSTED, /**< Too many stand-ins generated for the given variable range */ U_VARIABLE_RANGE_OVERLAP, /**< The variable range overlaps characters used in rules */ U_ILLEGAL_CHARACTER, /**< A special character is outside its allowed context */ U_INTERNAL_TRANSLITERATOR_ERROR, /**< Internal transliterator system error */ U_INVALID_ID, /**< A "::id" rule specifies an unknown transliterator */ U_INVALID_FUNCTION, /**< A "&fn()" rule specifies an unknown transliterator */ U_PARSE_ERROR_LIMIT, /**< The limit for Transliterator errors */ /* * the error code range 0x10100 0x10200 are reserved for formatting API parsing error */ U_UNEXPECTED_TOKEN=0x10100, /**< Syntax error in format pattern */ U_FMT_PARSE_ERROR_START=0x10100, /**< Start of format library errors */ U_MULTIPLE_DECIMAL_SEPARATORS, /**< More than one decimal separator in number pattern */ U_MULTIPLE_DECIMAL_SEPERATORS = U_MULTIPLE_DECIMAL_SEPARATORS, /**< Typo: kept for backward compatibility. Use U_MULTIPLE_DECIMAL_SEPARATORS */ U_MULTIPLE_EXPONENTIAL_SYMBOLS, /**< More than one exponent symbol in number pattern */ U_MALFORMED_EXPONENTIAL_PATTERN, /**< Grouping symbol in exponent pattern */ U_MULTIPLE_PERCENT_SYMBOLS, /**< More than one percent symbol in number pattern */ U_MULTIPLE_PERMILL_SYMBOLS, /**< More than one permill symbol in number pattern */ U_MULTIPLE_PAD_SPECIFIERS, /**< More than one pad symbol in number pattern */ U_PATTERN_SYNTAX_ERROR, /**< Syntax error in format pattern */ U_ILLEGAL_PAD_POSITION, /**< Pad symbol misplaced in number pattern */ U_UNMATCHED_BRACES, /**< Braces do not match in message pattern */ U_UNSUPPORTED_PROPERTY, /**< UNUSED as of ICU 2.4 */ U_UNSUPPORTED_ATTRIBUTE, /**< UNUSED as of ICU 2.4 */ U_ARGUMENT_TYPE_MISMATCH, /**< Argument name and argument index mismatch in MessageFormat functions */ U_DUPLICATE_KEYWORD, /**< Duplicate keyword in PluralFormat */ U_UNDEFINED_KEYWORD, /**< Undefined Plural keyword */ U_DEFAULT_KEYWORD_MISSING, /**< Missing DEFAULT rule in plural rules */ U_DECIMAL_NUMBER_SYNTAX_ERROR, /**< Decimal number syntax error */ U_FMT_PARSE_ERROR_LIMIT, /**< The limit for format library errors */ /* * the error code range 0x10200 0x102ff are reserved for Break Iterator related error */ U_BRK_INTERNAL_ERROR=0x10200, /**< An internal error (bug) was detected. */ U_BRK_ERROR_START=0x10200, /**< Start of codes indicating Break Iterator failures */ U_BRK_HEX_DIGITS_EXPECTED, /**< Hex digits expected as part of a escaped char in a rule. */ U_BRK_SEMICOLON_EXPECTED, /**< Missing ';' at the end of a RBBI rule. */ U_BRK_RULE_SYNTAX, /**< Syntax error in RBBI rule. */ U_BRK_UNCLOSED_SET, /**< UnicodeSet witing an RBBI rule missing a closing ']'. */ U_BRK_ASSIGN_ERROR, /**< Syntax error in RBBI rule assignment statement. */ U_BRK_VARIABLE_REDFINITION, /**< RBBI rule $Variable redefined. */ U_BRK_MISMATCHED_PAREN, /**< Mis-matched parentheses in an RBBI rule. */ U_BRK_NEW_LINE_IN_QUOTED_STRING, /**< Missing closing quote in an RBBI rule. */ U_BRK_UNDEFINED_VARIABLE, /**< Use of an undefined $Variable in an RBBI rule. */ U_BRK_INIT_ERROR, /**< Initialization failure. Probable missing ICU Data. */ U_BRK_RULE_EMPTY_SET, /**< Rule contains an empty Unicode Set. */ U_BRK_UNRECOGNIZED_OPTION, /**< !!option in RBBI rules not recognized. */ U_BRK_MALFORMED_RULE_TAG, /**< The {nnn} tag on a rule is mal formed */ U_BRK_ERROR_LIMIT, /**< This must always be the last value to indicate the limit for Break Iterator failures */ /* * The error codes in the range 0x10300-0x103ff are reserved for regular expression related errrs */ U_REGEX_INTERNAL_ERROR=0x10300, /**< An internal error (bug) was detected. */ U_REGEX_ERROR_START=0x10300, /**< Start of codes indicating Regexp failures */ U_REGEX_RULE_SYNTAX, /**< Syntax error in regexp pattern. */ U_REGEX_INVALID_STATE, /**< RegexMatcher in invalid state for requested operation */ U_REGEX_BAD_ESCAPE_SEQUENCE, /**< Unrecognized backslash escape sequence in pattern */ U_REGEX_PROPERTY_SYNTAX, /**< Incorrect Unicode property */ U_REGEX_UNIMPLEMENTED, /**< Use of regexp feature that is not yet implemented. */ U_REGEX_MISMATCHED_PAREN, /**< Incorrectly nested parentheses in regexp pattern. */ U_REGEX_NUMBER_TOO_BIG, /**< Decimal number is too large. */ U_REGEX_BAD_INTERVAL, /**< Error in {min,max} interval */ U_REGEX_MAX_LT_MIN, /**< In {min,max}, max is less than min. */ U_REGEX_INVALID_BACK_REF, /**< Back-reference to a non-existent capture group. */ U_REGEX_INVALID_FLAG, /**< Invalid value for match mode flags. */ U_REGEX_LOOK_BEHIND_LIMIT, /**< Look-Behind pattern matches must have a bounded maximum length. */ U_REGEX_SET_CONTAINS_STRING, /**< Regexps cannot have UnicodeSets containing strings.*/ U_REGEX_OCTAL_TOO_BIG, /**< Octal character constants must be <= 0377. */ U_REGEX_MISSING_CLOSE_BRACKET, /**< Missing closing bracket on a bracket expression. */ U_REGEX_INVALID_RANGE, /**< In a character range [x-y], x is greater than y. */ U_REGEX_STACK_OVERFLOW, /**< Regular expression backtrack stack overflow. */ U_REGEX_TIME_OUT, /**< Maximum allowed match time exceeded */ U_REGEX_STOPPED_BY_CALLER, /**< Matching operation aborted by user callback fn. */ U_REGEX_ERROR_LIMIT, /**< This must always be the last value to indicate the limit for regexp errors */ /* * The error code in the range 0x10400-0x104ff are reserved for IDNA related error codes */ U_IDNA_PROHIBITED_ERROR=0x10400, U_IDNA_ERROR_START=0x10400, U_IDNA_UNASSIGNED_ERROR, U_IDNA_CHECK_BIDI_ERROR, U_IDNA_STD3_ASCII_RULES_ERROR, U_IDNA_ACE_PREFIX_ERROR, U_IDNA_VERIFICATION_ERROR, U_IDNA_LABEL_TOO_LONG_ERROR, U_IDNA_ZERO_LENGTH_LABEL_ERROR, U_IDNA_DOMAIN_NAME_TOO_LONG_ERROR, U_IDNA_ERROR_LIMIT, /* * Aliases for StringPrep */ U_STRINGPREP_PROHIBITED_ERROR = U_IDNA_PROHIBITED_ERROR, U_STRINGPREP_UNASSIGNED_ERROR = U_IDNA_UNASSIGNED_ERROR, U_STRINGPREP_CHECK_BIDI_ERROR = U_IDNA_CHECK_BIDI_ERROR, /* * The error code in the range 0x10500-0x105ff are reserved for Plugin related error codes */ U_PLUGIN_ERROR_START=0x10500, /**< Start of codes indicating plugin failures */ U_PLUGIN_TOO_HIGH=0x10500, /**< The plugin's level is too high to be loaded right now. */ U_PLUGIN_DIDNT_SET_LEVEL, /**< The plugin didn't call uplug_setPlugLevel in response to a QUERY */ U_PLUGIN_ERROR_LIMIT, /**< This must always be the last value to indicate the limit for plugin errors */ U_ERROR_LIMIT=U_PLUGIN_ERROR_LIMIT /**< This must always be the last value to indicate the limit for UErrorCode (last error code +1) */ } UErrorCode;