iconv函数
转载自百度文库
头文件"iconv.h"。iconv命令可以将一种已知的字符集文件转换成另一种已知的字符集文件。
它的作用是在多种国际编码格式之间进行文本 内码的转换。
linux下的 函数原型
size_t iconv(iconv_t cd, char **inbuf, size_t *inbytesleft, char **outbuf, size_t *outbytesleft);
iconv是一个计算机程序以及一套 应用程序编程接口的名称。
作为应用程序的iconv采用 命令行界面，允许将某种特定编码的文件转换为另一种编码。
iconv基于 GPL公开源代码，是 GNU项目的一部分。在各种 UNIX操作系统下均可使用，而在 Windows系统，需要特殊的环境如 cygwin或者GnuWin32等软件平台下方可使用。现在在 SourceForge上也有运行于Windows系统的，需要同时安装 gettext程序。
目前版本为2.3.26，支持的 内码包括： Unicode相关编码，如UTF-8、 UTF-16等等，各国采用的 ANSI编码，其中包括 GB2312、 BIG5等中文编码方式。
主要内容
作为 编程接口的iconv包括3个 函数：
iconv_open 函数用于初始化用于转换的内部 缓冲区，需要指明需要从何种编码方式转换到哪一种。
iconv 函数进行实际的转换，需要给出两个间接 缓冲区 指针和剩余字节数指针。该 函数需要更新所有相关信息，因此将不可改写的 指针传递给iconv是错误的。
iconv_close 函数释放iconv_open函数的 缓冲区。
2、linux
命令说明：
iconv命令是用来转换文件的编码方式，比如可以将UTF8编码的转换成GB18030的编码，反过来也行。JDK中也提供了类似的工具native2ascii。Linux下的iconv开发库包括iconv_open,iconv_close,iconv等C函数，可以用来在C/C++程序中很方便的转换字符编码，这在抓取网页的程序中很有用处，而iconv命令在调试此类程序时用得着。
用法：
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iconv [选项...] [文件...]
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选项：
输入/输出格式规范：
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-f，--from-code=NAME 始文本编码
-t, --to-code=NAME 输出编码
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信息：
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-l, --list 列举所有已知的字符集
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输出控制：
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-c 从输出中忽略无效的字符
-o, --output=FILE 输出文件
-s, --silent suppress warnings
--verbose 打印进度信息
-?, --help 给出该系统求助列表
--usage 给出简要的用法信息
-V, --version 打印程序版本号
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示例：
列出支持的字符编码
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[root@new55 ~]# iconv -l
The following list contain all the coded character sets known. This does
not necessarily mean that all combinations of these names can be used for
the FROM and TO command line parameters. One coded character set can be
listed with several different names (aliases).
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所有已知字符集
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437, 500, 500V1, 850, 851, 852, 855, 856, 857, 860, 861, 862, 863, 864, 865,
866, 866NAV, 869, 874, 904, 1026, 1046, 1047, 8859_1, 8859_2, 8859_3, 8859_4,
8859_5, 8859_6, 8859_7, 8859_8, 8859_9, 10646-1:1993, 10646-1:1993/UCS4,
ANSI_X3.4-1968, ANSI_X3.4-1986, ANSI_X3.4, ANSI_X3.110-1983, ANSI_X3.110,
ARABIC, ARABIC7, ARMSCII-8, ASCII, ASMO-708, ASMO_449, BALTIC, BIG-5,
BIG-FIVE, BIG5-HKSCS, BIG5, BIG5HKSCS, BIGFIVE, BS_4730, CA, CN-BIG5, CN-GB,
CN, CP-AR, CP-GR, CP-HU, CP037, CP038, CP273, CP274, CP275, CP278, CP280,
CP281, CP282, CP284, CP285, CP290, CP297, CP367, CP420, CP423, CP424, CP437,
CP500, CP737, CP775, CP813, CP819, CP850, CP851, CP852, CP855, CP856, CP857,
CP860, CP861, CP862, CP863, CP864, CP865, CP866, CP866NAV, CP868, CP869,
CP870, CP871, CP874, CP875, CP880, CP891, CP903, CP904, CP905, CP912, CP915,
CP916, CP918, CP920, CP922, CP930, CP932, CP933, CP935, CP936, CP937, CP939,
CP949, CP950, CP1004, CP1026, CP1046, CP1047, CP1070, CP1079, CP1081, CP1084,
CP1089, CP1124, CP1125, CP1129, CP1132, CP1133, CP1160, CP1161, CP1162,
CP1163, CP1164, CP1250, CP1251, CP1252, CP1253, CP1254, CP1255, CP1256,
CP1257, CP1258, CP1361, CP10007, CPIBM861, CSA7-1, CSA7-2, CSASCII,
CSA_T500-1983, CSA_T500, CSA_Z243.4-1985-1, CSA_Z243.4-1985-2,
CSA_Z243.419851, CSA_Z243.419852, CSDECMCS, CSEBCDICATDE, CSEBCDICATDEA,
CSEBCDICCAFR, CSEBCDICDKNO, CSEBCDICDKNOA, CSEBCDICES, CSEBCDICESA,
CSEBCDICESS, CSEBCDICFISE, CSEBCDICFISEA, CSEBCDICFR, CSEBCDICIT, CSEBCDICPT,
CSEBCDICUK, CSEBCDICUS, CSEUCKR, CSEUCPKDFMTJAPANESE, CSGB2312, CSHPROMAN8,
CSIBM037, CSIBM038, CSIBM273, CSIBM274, CSIBM275, CSIBM277, CSIBM278,
CSIBM280, CSIBM281, CSIBM284, CSIBM285, CSIBM290, CSIBM297, CSIBM420,
CSIBM423, CSIBM424, CSIBM500, CSIBM851, CSIBM855, CSIBM856, CSIBM857,
CSIBM860, CSIBM863, CSIBM864, CSIBM865, CSIBM866, CSIBM868, CSIBM869,
CSIBM870, CSIBM871, CSIBM880, CSIBM891, CSIBM903, CSIBM904, CSIBM905,
CSIBM918, CSIBM922, CSIBM930, CSIBM932, CSIBM933, CSIBM935, CSIBM937,
CSIBM939, CSIBM943, CSIBM1026, CSIBM1124, CSIBM1129, CSIBM1132, CSIBM1133,
CSIBM1160, CSIBM1161, CSIBM1163, CSIBM1164, CSIBM11621162,
CSISO4UNITEDKINGDOM, CSISO10SWEDISH, CSISO11SWEDISHFORNAMES,
CSISO14JISC6220RO, CSISO15ITALIAN, CSISO16PORTUGESE, CSISO17SPANISH,
CSISO18GREEK7OLD, CSISO19LATINGREEK, CSISO21GERMAN, CSISO25FRENCH,
CSISO27LATINGREEK1, CSISO49INIS, CSISO50INIS8, CSISO51INISCYRILLIC,
CSISO58GB1988, CSISO60DANISHNORWEGIAN, CSISO60NORWEGIAN1, CSISO61NORWEGIAN2,
CSISO69FRENCH, CSISO84PORTUGUESE2, CSISO85SPANISH2, CSISO86HUNGARIAN,
CSISO88GREEK7, CSISO89ASMO449, CSISO90, CSISO92JISC62991984B, CSISO99NAPLPS,
CSISO103T618BIT, CSISO111ECMACYRILLIC, CSISO121CANADIAN1, CSISO122CANADIAN2,
CSISO139CSN369103, CSISO141JUSIB1002, CSISO143IECP271, CSISO150,
CSISO150GREEKCCITT, CSISO151CUBA, CSISO153GOST1976874, CSISO646DANISH,
CSISO2022CN, CSISO2022JP, CSISO2022JP2, CSISO2022KR, CSISO2033,
CSISO5427CYRILLIC, CSISO5427CYRILLIC1981, CSISO5428GREEK, CSISO10367BOX,
CSISOLATIN1, CSISOLATIN2, CSISOLATIN3, CSISOLATIN4, CSISOLATIN5, CSISOLATIN6,
CSISOLATINARABIC, CSISOLATINCYRILLIC, CSISOLATINGREEK, CSISOLATINHEBREW,
CSKOI8R, CSKSC5636, CSMACINTOSH, CSNATSDANO, CSNATSSEFI, CSN_369103,
CSPC8CODEPAGE437, CSPC775BALTIC, CSPC850MULTILINGUAL, CSPC862LATINHEBREW,
CSPCP852, CSSHIFTJIS, CSUCS4, CSUNICODE, CUBA, CWI-2, CWI, CYRILLIC, DE,
DEC-MCS, DEC, DECMCS, DIN_66003, DK, DS2089, DS_2089, E13B, EBCDIC-AT-DE-A,
EBCDIC-AT-DE, EBCDIC-BE, EBCDIC-BR, EBCDIC-CA-FR, EBCDIC-CP-AR1,
EBCDIC-CP-AR2, EBCDIC-CP-BE, EBCDIC-CP-CA, EBCDIC-CP-CH, EBCDIC-CP-DK,
EBCDIC-CP-ES, EBCDIC-CP-FI, EBCDIC-CP-FR, EBCDIC-CP-GB, EBCDIC-CP-GR,
EBCDIC-CP-HE, EBCDIC-CP-IS, EBCDIC-CP-IT, EBCDIC-CP-NL, EBCDIC-CP-NO,
EBCDIC-CP-ROECE, EBCDIC-CP-SE, EBCDIC-CP-TR, EBCDIC-CP-US, EBCDIC-CP-WT,
EBCDIC-CP-YU, EBCDIC-CYRILLIC, EBCDIC-DK-NO-A, EBCDIC-DK-NO, EBCDIC-ES-A,
EBCDIC-ES-S, EBCDIC-ES, EBCDIC-FI-SE-A, EBCDIC-FI-SE, EBCDIC-FR,
EBCDIC-GREEK, EBCDIC-INT, EBCDIC-INT1, EBCDIC-IS-FRISS, EBCDIC-IT,
EBCDIC-JP-E, EBCDIC-JP-KANA, EBCDIC-PT, EBCDIC-UK, EBCDIC-US, EBCDICATDE,
EBCDICATDEA, EBCDICCAFR, EBCDICDKNO, EBCDICDKNOA, EBCDICES, EBCDICESA,
EBCDICESS, EBCDICFISE, EBCDICFISEA, EBCDICFR, EBCDICISFRISS, EBCDICIT,
EBCDICPT, EBCDICUK, EBCDICUS, ECMA-114, ECMA-118, ECMA-128, ECMA-CYRILLIC,
ECMACYRILLIC, ELOT_928, ES, ES2, EUC-CN, EUC-JISX0213, EUC-JP, EUC-KR,
EUC-TW, EUCCN, EUCJP, EUCKR, EUCTW, FI, FR, GB, GB2312, GB13000, GB18030,
GBK, GB_1988-80, GB_198880, GEORGIAN-ACADEMY, GEORGIAN-PS, GOST_19768-74,
GOST_19768, GOST_1976874, GREEK-CCITT, GREEK, GREEK7-OLD, GREEK7, GREEK7OLD,
GREEK8, GREEKCCITT, HEBREW, HP-ROMAN8, HPROMAN8, HU, IBM-856, IBM-922,
IBM-930, IBM-932, IBM-933, IBM-935, IBM-937, IBM-939, IBM-943, IBM-1046,
IBM-1124, IBM-1129, IBM-1132, IBM-1133, IBM-1160, IBM-1161, IBM-1162,
IBM-1163, IBM-1164, IBM037, IBM038, IBM256, IBM273, IBM274, IBM275, IBM277,
IBM278, IBM280, IBM281, IBM284, IBM285, IBM290, IBM297, IBM367, IBM420,
IBM423, IBM424, IBM437, IBM500, IBM775, IBM813, IBM819, IBM848, IBM850,
IBM851, IBM852, IBM855, IBM856, IBM857, IBM860, IBM861, IBM862, IBM863,
IBM864, IBM865, IBM866, IBM866NAV, IBM868, IBM869, IBM870, IBM871, IBM874,
IBM875, IBM880, IBM891, IBM903, IBM904, IBM905, IBM912, IBM915, IBM916,
IBM918, IBM920, IBM922, IBM930, IBM932, IBM933, IBM935, IBM937, IBM939,
IBM943, IBM1004, IBM1026, IBM1046, IBM1047, IBM1089, IBM1124, IBM1129,
IBM1132, IBM1133, IBM1160, IBM1161, IBM1162, IBM1163, IBM1164, IEC_P27-1,
IEC_P271, INIS-8, INIS-CYRILLIC, INIS, INIS8, INISCYRILLIC, ISIRI-3342,
ISIRI3342, ISO-2022-CN-EXT, ISO-2022-CN, ISO-2022-JP-2, ISO-2022-JP-3,
ISO-2022-JP, ISO-2022-KR, ISO-8859-1, ISO-8859-2, ISO-8859-3, ISO-8859-4,
ISO-8859-5, ISO-8859-6, ISO-8859-7, ISO-8859-8, ISO-8859-9, ISO-8859-10,
ISO-8859-11, ISO-8859-13, ISO-8859-14, ISO-8859-15, ISO-8859-16, ISO-10646,
ISO-10646/UCS2, ISO-10646/UCS4, ISO-10646/UTF-8, ISO-10646/UTF8, ISO-CELTIC,
ISO-IR-4, ISO-IR-6, ISO-IR-8-1, ISO-IR-9-1, ISO-IR-10, ISO-IR-11, ISO-IR-14,
ISO-IR-15, ISO-IR-16, ISO-IR-17, ISO-IR-18, ISO-IR-19, ISO-IR-21, ISO-IR-25,
ISO-IR-27, ISO-IR-37, ISO-IR-49, ISO-IR-50, ISO-IR-51, ISO-IR-54, ISO-IR-55,
ISO-IR-57, ISO-IR-60, ISO-IR-61, ISO-IR-69, ISO-IR-84, ISO-IR-85, ISO-IR-86,
ISO-IR-88, ISO-IR-89, ISO-IR-90, ISO-IR-92, ISO-IR-98, ISO-IR-99, ISO-IR-100,
ISO-IR-101, ISO-IR-103, ISO-IR-109, ISO-IR-110, ISO-IR-111, ISO-IR-121,
ISO-IR-122, ISO-IR-126, ISO-IR-127, ISO-IR-138, ISO-IR-139, ISO-IR-141,
ISO-IR-143, ISO-IR-144, ISO-IR-148, ISO-IR-150, ISO-IR-151, ISO-IR-153,
ISO-IR-155, ISO-IR-156, ISO-IR-157, ISO-IR-166, ISO-IR-179, ISO-IR-193,
ISO-IR-197, ISO-IR-199, ISO-IR-203, ISO-IR-209, ISO-IR-226, ISO646-CA,
ISO646-CA2, ISO646-CN, ISO646-CU, ISO646-DE, ISO646-DK, ISO646-ES,
ISO646-ES2, ISO646-FI, ISO646-FR, ISO646-FR1, ISO646-GB, ISO646-HU,
ISO646-IT, ISO646-JP-OCR-B, ISO646-JP, ISO646-KR, ISO646-NO, ISO646-NO2,
ISO646-PT, ISO646-PT2, ISO646-SE, ISO646-SE2, ISO646-US, ISO646-YU,
ISO2022CN, ISO2022CNEXT, ISO2022JP, ISO2022JP2, ISO2022KR, ISO6937,
ISO8859-1, ISO8859-2, ISO8859-3, ISO8859-4, ISO8859-5, ISO8859-6, ISO8859-7,
ISO8859-8, ISO8859-9, ISO8859-10, ISO8859-11, ISO8859-13, ISO8859-14,
ISO8859-15, ISO8859-16, ISO88591, ISO88592, ISO88593, ISO88594, ISO88595,
ISO88596, ISO88597, ISO88598, ISO88599, ISO885910, ISO885911, ISO885913,
ISO885914, ISO885915, ISO885916, ISO_646.IRV:1991, ISO_2033-1983, ISO_2033,
ISO_5427-EXT, ISO_5427, ISO_5427:1981, ISO_5427EXT, ISO_5428, ISO_5428:1980,
ISO_6937-2, ISO_6937-2:1983, ISO_6937, ISO_6937:1992, ISO_8859-1,
ISO_8859-1:1987, ISO_8859-2, ISO_8859-2:1987, ISO_8859-3, ISO_8859-3:1988,
ISO_8859-4, ISO_8859-4:1988, ISO_8859-5, ISO_8859-5:1988, ISO_8859-6,
ISO_8859-6:1987, ISO_8859-7, ISO_8859-7:1987, ISO_8859-8, ISO_8859-8:1988,
ISO_8859-9, ISO_8859-9:1989, ISO_8859-10,ISO_8859-10:1992, ISO_8859-14,
ISO_8859-14:1998, ISO_8859-15:1998, ISO_9036, ISO_10367-BOX, ISO_10367BOX,
ISO_69372, IT, JIS_C6220-1969-RO, JIS_C6229-1984-B, JIS_C62201969RO,
JIS_C62291984B, JOHAB, JP-OCR-B, JP, JS, JUS_I.B1.002, KOI-7, KOI-8, KOI8-R,
KOI8-T, KOI8-U, KOI8, KOI8R, KOI8U, KSC5636, L1, L2, L3, L4, L5, L6, L7, L8,
L10, LATIN-GREEK-1, LATIN-GREEK, LATIN1, LATIN2, LATIN3, LATIN4, LATIN5,
LATIN6, LATIN7, LATIN8, LATIN10, LATINGREEK, LATINGREEK1, MAC-CYRILLIC,
MAC-IS, MAC-SAMI, MAC-UK, MAC, MACCYRILLIC, MACINTOSH, MACIS, MACUK,
MACUKRAINIAN, MS-ANSI, MS-ARAB, MS-CYRL, MS-EE, MS-GREEK, MS-HEBR,
MS-MAC-CYRILLIC, MS-TURK, MSCP949, MSCP1361, MSMACCYRILLIC, MSZ_7795.3,
MS_KANJI, NAPLPS, NATS-DANO, NATS-SEFI, NATSDANO, NATSSEFI, NC_NC0010,
NC_NC00-10, NC_NC00-10:81, NF_Z_62-010, NF_Z_62-010_(1973), NF_Z_62-010_1973,
NF_Z_62010, NF_Z_62010_1973, NO, NO2, NS_4551-1, NS_4551-2, NS_45511,
NS_45512, OS2LATIN1, OSF00010001, OSF00010002, OSF00010003, OSF00010004,
OSF00010005, OSF00010006, OSF00010007, OSF00010008, OSF00010009, OSF0001000A,
OSF00010020, OSF00010100, OSF00010101, OSF00010102, OSF00010104, OSF00010105,
OSF00010106, OSF00030010, OSF0004000A, OSF0005000A, OSF05010001, OSF100201A4,
OSF100201A8, OSF100201B5, OSF100201F4, OSF100203B5, OSF1002011C, OSF1002011D,
OSF1002035D, OSF1002035E, OSF1002035F, OSF1002036B, OSF1002037B, OSF10010001,
OSF10020025, OSF10020111, OSF10020115, OSF10020116, OSF10020118, OSF10020122,
OSF10020129, OSF10020352, OSF10020354, OSF10020357, OSF10020359, OSF10020360,
OSF10020364, OSF10020365, OSF10020366, OSF10020367, OSF10020370, OSF10020387,
OSF10020388, OSF10020396, OSF10020402, OSF10020417, PT, PT2, R8, ROMAN8,
RUSCII, SE, SE2, SEN_850200_B, SEN_850200_C, SHIFT-JIS, SHIFT_JIS,
SHIFT_JISX0213, SJIS, SS636127, ST_SEV_358-88, T.61-8BIT, T.61, T.618BIT,
TCVN-5712, TCVN, TCVN5712-1, TCVN5712-1:1993, TIS-620, TIS620-0,
TIS620.2529-1, TIS620.2533-0, TIS620, TS-5881, TSCII, UCS-2, UCS-2BE,
UCS-2LE, UCS-4, UCS-4BE, UCS-4LE, UCS2, UCS4, UHC, UJIS, UK, UNICODE,
UNICODEBIG, UNICODELITTLE, US-ASCII, US, UTF-7, UTF-8, UTF-16, UTF-16BE,
UTF-16LE, UTF-32, UTF-32BE, UTF-32LE, UTF7, UTF8, UTF16, UTF16BE, UTF16LE,
UTF32, UTF32BE, UTF32LE, VISCII, WCHAR_T, WIN-SAMI-2, WINBALTRIM,
WINDOWS-1250, WINDOWS-1251, WINDOWS-1252, WINDOWS-1253, WINDOWS-1254,
WINDOWS-1255, WINDOWS-1256, WINDOWS-1257, WINDOWS-1258, WINSAMI2, WS2, YU
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指令：
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#iconv -f gb2312 -t utf8 gb1.txt > gb2.txt
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将gb1里的编码从GB2312转化成UTF-8 并重定向到gb2.txt
除了iconv命令，我们在 linux系统下的man page的第三节还可以看到一组iconv函数。它们分别是
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iconv_t iconv_open(
const
char
*tocode,
const
char
*fromcode);
size_ticonv(iconv_t cd,
char
**inbuf,
size_t
*inbytesleft,
char
**outbuf,
size_t
*outbytesleft);
int
iconv_close(iconv_t cd);
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iconv_open 函数用来打开一个编码转换的流，iconv函数的作用是实际进行转换，iconv_close函数的作用就是关闭这个流。实际用法参见下面的例子，下面是一个将UTF-8码转换成GBK码的例子，我们假设已经有了一个uft8编码的 输入 缓冲区inbuf以及这个缓冲区的长度inlen。
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iconv_t cd = iconv_open(
"GBK"
,
"UTF-8"
);
char
*outbuf = (
char
*)
malloc
(inlen * 4 );
bzero( outbuf, inlen * 4);
char
*in = inbuf;
char
*out = outbuf;
size_t
outlen = inlen *4;
iconv（cd, &in, (
size_t
*)&inlen, &out,&outlen）;
outlen =
strlen
(outbuf);
printf
(
"%s\n"
,outbuf);
free
(outbuf);
iconv_close(cd);
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非常值得注意的地方是：iconv 函数会修改参数in和参数out 指针所指向的地方，也就是说，在调用iconv函数之前，我们的in和inbuf指针以及out和outbuf指针指向的是同一块内存区域，但是调用之后out指针所指向的地方就不是outbuf了，同理in指针。所以要
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char
*in = inbuf;
char
*out = outbuf;
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另存一下，使用或者释放内存的时候也要使用原先的那个 指针outbuf和inbuf。