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iconv convert
#include <iostream>
#include <iconv.h>
#include <stdlib.h>
#include <string.h>
#include <sys/errno.h>
using namespace std;
char *
convert(const char *from_charset, const char *to_charset, const char *input) {
size_t inleft, outleft, converted = 0;
char *output, *outbuf, *tmp;
const char *inbuf;
size_t outlen;
iconv_t cd;
int errno;
if ((cd = iconv_open(to_charset, from_charset)) == (iconv_t) -1)
return NULL;
inleft = strlen(input);
inbuf = input;
/* we'll start off allocating an output buffer which is the same size
* as our input buffer. */
outlen = inleft;
/* we allocate 4 bytes more than what we need for nul-termination... */
if (!(output = (char*) malloc(outlen + 4))) {
iconv_close(cd);
return NULL;
}
do {
errno = 0;
outbuf = output + converted;
outleft = outlen - converted;
converted = iconv(cd, (char **) &inbuf, &inleft, &outbuf, &outleft);
if (converted != (size_t) -1 || errno == EINVAL) {
/*
* EINVAL An incomplete multibyte sequence has been encoun­-
* tered in the input.
*
* We'll just truncate it and ignore it.
*/
break;
}
if (errno != E2BIG) {
/*
* EILSEQ An invalid multibyte sequence has been encountered
* in the input.
*
* Bad input, we can't really recover from this.
*/
iconv_close(cd);
free(output);
return NULL;
}
/*
* E2BIG There is not sufficient room at *outbuf.
*
* We just need to grow our outbuffer and try again.
*/
converted = outbuf - output;
outlen += inleft * 2 + 8;
if (!(tmp = (char*) realloc(output, outlen + 4))) {
iconv_close(cd);
free(output);
return NULL;
}
output = tmp;
outbuf = output + converted;
} while (1);
/* flush the iconv conversion */
iconv(cd, NULL, NULL, &outbuf, &outleft);
iconv_close(cd);
/* Note: not all charsets can be nul-terminated with a single
* nul byte. UCS2, for example, needs 2 nul bytes and UCS4
* needs 4. I hope that 4 nul bytes is enough to terminate all
* multibyte charsets? */
/* nul-terminate the string */
memset(outbuf, 0, 4);
return output;
}
int main() {
string input = string("Test æøå a");
char* outoutBuffer;
outoutBuffer = convert("UTF-8", "ISO-8859-1", input.c_str());
string output = string(outoutBuffer);
cout << input << endl;
cout << output << endl;
return 0;
}
@guame

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@guame guame commented Sep 18, 2018

Hello, thanks a lot for this nice example, the cleaner I found so far for iconv !
Just a question with the realloc. I'm not very fluent with C and I found that realloc could be tricky in some case:
https://stackoverflow.com/questions/44789295/correct-use-of-realloc
Do you think it worth it to use this double pointer or is it too much ?

@DCastellacci

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@DCastellacci DCastellacci commented Sep 2, 2019

Thank you for your code this help me for my project c ++ to print in a terminal TM T20II epson ticket

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