How do I HTML-/ URL-Encode a std::wstring containing Unicode characters? - c++

Question

I have another question yet. If I had a std::wstring looking like this:
ドイツ語で検索していてこちらのサイトにたどり着きました。
How could I possibly get it to be URL-Encoded (%nn, n = 0-9, a-f) to:
%E3%83%89%E3%82%A4%E3%83%84%E8%AA%9E%E3%81%A7%E6%A4%9C%E7%B4%A2%E3%81%97%E3%81%A6%E3%81%84%E3%81%A6%E3%81%93%E3%81%A1%E3%82%89%E3%81%AE%E3%82%B5%E3%82%A4%E3%83%88%E3%81%AB%E3%81%9F%E3%81%A9%E3%82%8A%E7%9D%80%E3%81%8D%E3%81%BE%E3%81%97%E3%81%9F%E3%80%82
... and also HTML-Encoded (&#nnn(nn);, n = 0-9(?)) to:
ドイツ語で検索していてこちらのサイトにたどり着きました。
Please help me as I am totally lost right now and don't even know where to start. By the way, performance isn't much important to me right now.
Thanks in advance!

Answer 1

Here is an example which shows two methods, one based on the Qt library and one based on the ICU library. Both should be fairly platform-independent:
#include <iostream>
#include <sstream>
#include <iomanip>
#include <stdexcept>
#include <boost/scoped_array.hpp>
#include <QtCore/QString>
#include <QtCore/QUrl>
#include <QtCore/QVector>
#include <unicode/utypes.h>
#include <unicode/ustring.h>
#include <unicode/unistr.h>
#include <unicode/schriter.h>
void encodeQt() {
const QString str = QString::fromWCharArray(L"ドイツ語で検索していてこちらのサイトにたどり着きました。");
const QUrl url = str;
std::cout << "URL encoded: " << url.toEncoded().constData() << std::endl;
typedef QVector<uint> CodePointVector;
const CodePointVector codePoints = str.toUcs4();
std::stringstream htmlEncoded;
for (CodePointVector::const_iterator it = codePoints.constBegin(); it != codePoints.constEnd(); ++it) {
htmlEncoded << "&#" << *it << ';';
}
std::cout << "HTML encoded: " << htmlEncoded.str() << std::endl;
}
void encodeICU() {
const std::wstring cppString = L"ドイツ語で検索していてこちらのサイトにたどり着きました。";
int bufSize = cppString.length() * 2;
boost::scoped_array<UChar> strBuffer(new UChar[bufSize]);
int size = 0;
UErrorCode error = U_ZERO_ERROR;
u_strFromWCS(strBuffer.get(), bufSize, &size, cppString.data(), cppString.length(), &error);
if (error) return;
const UnicodeString str(strBuffer.get(), size);
bufSize = str.length() * 4;
boost::scoped_array<char> buffer(new char[bufSize]);
u_strToUTF8(buffer.get(), bufSize, &size, str.getBuffer(), str.length(), &error);
if (error) return;
const std::string urlUtf8(buffer.get(), size);
std::stringstream urlEncoded;
urlEncoded << std::hex << std::setfill('0');
for (std::string::const_iterator it = urlUtf8.begin(); it != urlUtf8.end(); ++it) {
urlEncoded << '%' << std::setw(2) << static_cast<unsigned int>(static_cast<unsigned char>(*it));
}
std::cout << "URL encoded: " << urlEncoded.str() << std::endl;
std::stringstream htmlEncoded;
StringCharacterIterator it = str;
while (it.hasNext()) {
const UChar32 pt = it.next32PostInc();
htmlEncoded << "&#" << pt << ';';
}
std::cout << "HTML encoded: " << htmlEncoded.str() << std::endl;
}
int main() {
encodeQt();
encodeICU();
}

Answer 2

You see, before you can convert a char to a URL escape sequence, you have to convert your wstring* into ISO-Latin charset which is what is used for URLs. ICU could be a good place to start, where you can pass your wstring to it and get a ISO-Lantin sequence. Then, simply iterate through the resulting chars and convert them to the escape senquence:
std::stringstream URL;
URL << std::hex;
for(auto it = myWString.begin(); it != myWString.end(); ++it)
URL << '%' << std::setfill('0') << std::setw(2) << (int)*it;
Take a look here for more info in how to format the string.
* I'm assuming that your wstring is a UTF-16, which usually is the case, although you didn't specify
This might help also.

Answer 3

Here's a version that converts from UTF-16 (wchar) to hex-encoded UTF-8 using the Win32-specific WideCharToMultiByte() function.
#include <string>
#include <iostream>
#include <stdio.h>
#include <windows.h>
std::string wstring_to_utf8_hex(const std::wstring &input)
{
std::string output;
int cbNeeded = WideCharToMultiByte(CP_UTF8, 0, input.c_str(), -1, NULL, 0, NULL, NULL);
if (cbNeeded > 0) {
char *utf8 = new char[cbNeeded];
if (WideCharToMultiByte(CP_UTF8, 0, input.c_str(), -1, utf8, cbNeeded, NULL, NULL) != 0) {
for (char *p = utf8; *p; *p++) {
char onehex[5];
_snprintf(onehex, sizeof(onehex), "%%%02.2X", (unsigned char)*p);
output.append(onehex);
}
}
delete[] utf8;
}
return output;
}
int main(int, char*[])
{
std::wstring ja = L"ドイツ語で検索していてこちらのサイトにたどり着きました。";
std::cout << "result=" << wstring_to_utf8_hex(ja) << std::endl;
return 0;
}
To go the other way, you'll need to use some parsing to decode the hex values into a UTF-8 buffer, and then call the complimentary MultiByteToWideChar() to get it back into a wchar array.
#include <string>
#include <iostream>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
std::string unhexlify(const std::string &input)
{
std::string output;
for (const char *p = input.c_str(); *p; ) {
if (p[0] == '%' && isxdigit(p[1]) && isxdigit(p[2])) {
int ch = (isdigit(p[1]) ? p[1] - '0' : toupper(p[1]) - 'A' + 10) * 16 +
(isdigit(p[2]) ? p[2] - '0' : toupper(p[2]) - 'A' + 10);
output.push_back((char)ch);
p += 3;
} else if (p[0] == '%' && p[1] == '#' && isdigit(p[2])) {
int ch = atoi(p + 2);
output.push_back((char)ch);
p += 2;
while (*p && isdigit(*p)) p++;
if (*p == ';') p++;
} else {
output.push_back(*p++);
}
}
return output;
}
std::wstring utf8_hex_to_wstring(const std::string &input)
{
std::wstring output;
std::string utf8 = unhexlify(input);
int cchNeeded = MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(), -1, NULL, 0);
if (cchNeeded > 0) {
wchar_t *widebuf = new wchar_t[cchNeeded];
if (MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(), -1, widebuf, cchNeeded) != 0) {
output = widebuf;
}
delete[] widebuf;
}
return output;
}
int main(int, char*[])
{
std::wstring ja = L"ドイツ語で検索していてこちらのサイトにたどり着きました。";
std::string hex = "%E3%83%89%E3%82%A4%E3%83%84%E8%AA%9E%E3%81%A7%E6%A4%9C%E7%B4%A2%E3%81%97%E3%81%A6%E3%81%84%E3%81%A6%E3%81%93%E3%81%A1%E3%82%89%E3%81%AE%E3%82%B5%E3%82%A4%E3%83%88%E3%81%AB%E3%81%9F%E3%81%A9%E3%82%8A%E7%9D%80%E3%81%8D%E3%81%BE%E3%81%97%E3%81%9F%E3%80%82";
std::wstring newja = utf8_hex_to_wstring(hex);
std::cout << "match?=" << (newja == ja ? "yes" : "no") << std::endl;
return 0;
}

Answer 4

First, convert to UTF-8.
Then, normal URL/HTML encode would do the right thing.

Answer 5

I find in C# it's simple, so I use C++\CLI as wrapper, wrap C# code:
string encodedStr = System.Web.HttpUtility.UrlEncode(inputstr);`
in C++\CLI make a method as __declspec(dllexport) so in C++ can call it, the C++\CLI syntax is:
String^ encodedStr = System::Web::HttpUtility::UrlEncode(inputStr);`.
this is a tutorial about how to call C++\CLI from C++: How to call a C# library from Native C++ (using C++\CLI and IJW)