Character Set conversion in Linux (utf8 conversion)

During encoding and conversion on Linux, you can use both the iconv function family programming and the iconv command, but the latter is for files, converts a specified file from one encoding to another.
I. Use the iconv function family for encoding and conversion
The header file of the iconv function family is iconv. H, which must be included before use.
# Include <iconv. h>
The iconv function family has three functions. The prototype is as follows:
(1) iconv_t iconv_open (const char * tocode, const char * fromcode );
This function indicates which two types of encoding are to be converted. tocode is the target encoding and fromcode is the original encoding. This function returns a conversion handle for the following two functions.
(2) size_t iconv (iconv_t CD, char ** inbuf, size_t * inbytesleft, char ** outbuf, size_t * outbytesleft );
This function reads characters from inbuf and outputs the converted characters to outbuf. inbytesleft records the number of characters that have not been converted, and outbytesleft records the remaining space of the output buffer.

(3) int iconv_close (iconv_t CD );
This function is used to close the conversion handle and release resources.
Example 1: A conversion example program implemented in C Language

/* F. C: Code Conversion example C program */Specifically, the implementation of self-verification is implemented according to the F. C in the article.
# Include <iconv. h>
# Deprecision outlen 255
Main ()
{
Char * in_utf8 = "e? Why ?? Why? "; <======= This string does not seem to be a reference string for utf8,
Char * in_gb2312 = "installing ";
Char out [outlen];

// Convert Unicode code to gb2312 code
Rc = u2g (in_utf8, strlen (in_utf8), Out, outlen );
Printf ("Unicode --> gb2312 out = % Sn", out );
// Convert the gb2312 code to the Unicode code
Rc = g2u (in_gb2312, strlen (in_gb2312), Out, outlen );
Printf ("gb2312 --> Unicode out = % Sn", out );
}
// Code Conversion: Convert from one encoding to another
Int code_convert (char * from_charset, char * to_charset, char * inbuf, int inlen, char * outbuf, int outlen)
{
Iconv_t CD;
Int RC;
Char ** pin = & inbuf;
Char ** pout = & outbuf;

Cd = iconv_open (to_charset, from_charset );
If (Cd = 0) Return-1;
Memset (outbuf, 0, outlen );
If (iconv (Cd, pin, & inlen, pout, & outlen) =-1) Return-1;
Iconv_close (CD );
Return 0;
}
// Convert Unicode code to gb2312 code
Int u2g (char * inbuf, int inlen, char * outbuf, int outlen)
{
Return code_convert ("UTF-8", "gb2312", inbuf, inlen, outbuf, outlen );
}
// Convert the gb2312 code to the Unicode code
Int g2u (char * inbuf, size_t inlen, char * outbuf, size_t outlen)
{
Return code_convert ("gb2312", "UTF-8", inbuf, inlen, outbuf, outlen );
}

Example 2: A conversion example program in C ++

/* F. cpp: Code Conversion example c ++ Program */
# Include <iconv. h>
# Include <iostream>

# Deprecision outlen 255

Using namespace STD;

// Code conversion operation class
Class codeconverter {
PRIVATE:
Iconv_t CD;
Public:
// Construct
Codeconverter (const char * from_charset, const char * to_charset ){
Cd = iconv_open (to_charset, from_charset );
}

// Structure
~ Codeconverter (){
Iconv_close (CD );
}

// Conversion output
Int convert (char * inbuf, int inlen, char * outbuf, int outlen ){
Char ** pin = & inbuf;
Char ** pout = & outbuf;

Memset (outbuf, 0, outlen );
Return iconv (Cd, pin, (size_t *) & inlen, pout, (size_t *) & outlen );
}
};

Int main (INT argc, char ** argv)
{
Char * in_utf8 = "e? Why ?? Why? ";
Char * in_gb2312 = "installing ";
Char out [outlen];

// UTF-8 --> gb2312
Codeconverter cc = codeconverter ("UTF-8", "gb2312 ");
Cc. Convert (in_utf8, strlen (in_utf8), Out, outlen );
Cout <"UTF-8 --> gb2312 in =" <in_utf8 <", out =" <out <Endl;

// Gb2312 --> UTF-8
Codeconverter CC2 = codeconverter ("gb2312", "UTF-8 ");
Cc2.convert (in_gb2312, strlen (in_gb2312), Out, outlen );
Cout <"gb2312 --> UTF-8 in =" <in_gb2312 <", out =" <out <Endl;
}

Ii. Use the iconv command for encoding and conversion

The iconv command is used to convert the encoding of a specified file. By default, it is output to a standard output device, or an output file.

Usage: iconv [option...] [file...]

The following options are available:

Input/output format specifications:
-F, -- from-code = Name Original Text Encoding
-T, -- to-code = Name output Encoding

Information:
-L, -- list lists all known character sets

Output Control:
-C: Ignore invalid characters from the output
-O, -- output = file: output file
-S, -- silent close warning
-- Verbose prints the progress information

-?, -- Help: Provides the system's help list
-- Usage provides brief usage information
-V, -- version print the program version number

Example:
Iconv-F UTF-8-T gb2312 aaa.txt> bbb.txt
This command reads the aaa.txt file and converts it from the 8th to the gb2312th file, and the output is directed to the bbb.txt file.