csdn C++实现utf8和gbk编码字符串互相转换

不同系统或者服务器之间消息传递经常遇到编码转换问题，这里用C++实现了一个轻量的gbk和utf8互相转换，可跨平台使用。（重量级的可以用libiconv库）

在windows下用<windows.h>头文件里的函数进行多字节和宽字符转换，linux下采用头文件里的函数进行编码互相解析。

#include <iostream>
#include <string>
#include <string.h>
#include <stdlib.h>

using namespace std;

#ifdef _WIN32
#include <windows.h>

string GbkToUtf8(const char *src_str)
{
    int len = MultiByteToWideChar(CP_ACP, 0, src_str, -1, NULL, 0);
    wchar_t* wstr = new wchar_t[len + 1];
    memset(wstr, 0, len + 1);
    MultiByteToWideChar(CP_ACP, 0, src_str, -1, wstr, len);
    len = WideCharToMultiByte(CP_UTF8, 0, wstr, -1, NULL, 0, NULL, NULL);
    char* str = new char[len + 1];
    memset(str, 0, len + 1);
    WideCharToMultiByte(CP_UTF8, 0, wstr, -1, str, len, NULL, NULL);
    string strTemp = str;
    if (wstr) delete[] wstr;
    if (str) delete[] str;
    return strTemp;
}

string Utf8ToGbk(const char *src_str)
{
    int len = MultiByteToWideChar(CP_UTF8, 0, src_str, -1, NULL, 0);
    wchar_t* wszGBK = new wchar_t[len + 1];
    memset(wszGBK, 0, len * 2 + 2);
    MultiByteToWideChar(CP_UTF8, 0, src_str, -1, wszGBK, len);
    len = WideCharToMultiByte(CP_ACP, 0, wszGBK, -1, NULL, 0, NULL, NULL);
    char* szGBK = new char[len + 1];
    memset(szGBK, 0, len + 1);
    WideCharToMultiByte(CP_ACP, 0, wszGBK, -1, szGBK, len, NULL, NULL);
    string strTemp(szGBK);
    if (wszGBK) delete[] wszGBK;
    if (szGBK) delete[] szGBK;
    return strTemp;
}
#else
#include <iconv.h>

int GbkToUtf8(char *str_str, size_t src_len, char *dst_str, size_t dst_len)
{
    iconv_t cd;
    char **pin = &str_str;
    char **pout = &dst_str;

    cd = iconv_open("utf8", "gbk");
    if (cd == 0)
        return -1;
    memset(dst_str, 0, dst_len);
    if (iconv(cd, pin, &src_len, pout, &dst_len) == -1)
        return -1;
    iconv_close(cd);
    *pout = '\0';

    return 0;
}

int Utf8ToGbk(char *src_str, size_t src_len, char *dst_str, size_t dst_len)
{
    iconv_t cd;
    char **pin = &src_str;
    char **pout = &dst_str;

    cd = iconv_open("gbk", "utf8");
    if (cd == 0)
        return -1;
    memset(dst_str, 0, dst_len);
    if (iconv(cd, pin, &src_len, pout, &dst_len) == -1)
        return -1;
    iconv_close(cd);
    *pout = '\0';

    return 0;
}

#endif

int main(void)
{
    char *src_str = "葡萄美酒夜光杯";
    cout << "origin string: " << src_str << endl;

#ifdef _WIN32
    // windows default is gbk
    string dst_str = GbkToUtf8(src_str);
    cout << "gbk to utf8: " << dst_str << endl;

    string str_utf8 = Utf8ToGbk(dst_str.c_str());
    cout << "utf8 to gbk: " << str_utf8 << endl;
#else
    // unix default is utf8
    char dst_gbk[1024] = { 0 };
    Utf8ToGbk(src_str, strlen(src_str), dst_gbk, sizeof(dst_gbk));
    cout << "utf8 to gbk: " << dst_gbk << endl;

    char dst_utf8[1024] = { 0 };
    GbkToUtf8(dst_gbk, strlen(dst_gbk), dst_utf8, sizeof(dst_utf8));
    cout << "gbk to utf8: " << dst_utf8 << endl;
#endif

    return 0;
}
// g++ test.cpp

NOTE:

1、编译报错如下:

test.cpp: In function 'int GbkToUtf8(char*, size_t, char*, size_t)':
test.cpp:58:10: error: invalid conversion from 'char' to 'char*' [-fpermissive]
  *pout = '\0';
          ^~~~
test.cpp: In function 'int Utf8ToGbk(char*, size_t, char*, size_t)':
test.cpp:76:10: error: invalid conversion from 'char' to 'char*' [-fpermissive]
  *pout = '\0';
          ^~~~
test.cpp: In function 'int main()':
test.cpp:85:18: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
  char *src_str = "葡萄美酒夜光杯";
                  ^~~~~~~~~~~~~~~~

修正的程序

#include <iostream>
#include <string>
#include <string.h>
#include <stdlib.h>

using namespace std;

#ifdef _WIN32
#include <windows.h>

string GbkToUtf8(const char *src_str)
{
    int len = MultiByteToWideChar(CP_ACP, 0, src_str, -1, NULL, 0);
    wchar_t* wstr = new wchar_t[len + 1];
    memset(wstr, 0, len + 1);
    MultiByteToWideChar(CP_ACP, 0, src_str, -1, wstr, len);
    len = WideCharToMultiByte(CP_UTF8, 0, wstr, -1, NULL, 0, NULL, NULL);
    char* str = new char[len + 1];
    memset(str, 0, len + 1);
    WideCharToMultiByte(CP_UTF8, 0, wstr, -1, str, len, NULL, NULL);
    string strTemp = str;
    if (wstr) delete[] wstr;
    if (str) delete[] str;
    return strTemp;
}

string Utf8ToGbk(const char *src_str)
{
    int len = MultiByteToWideChar(CP_UTF8, 0, src_str, -1, NULL, 0);
    wchar_t* wszGBK = new wchar_t[len + 1];
    memset(wszGBK, 0, len * 2 + 2);
    MultiByteToWideChar(CP_UTF8, 0, src_str, -1, wszGBK, len);
    len = WideCharToMultiByte(CP_ACP, 0, wszGBK, -1, NULL, 0, NULL, NULL);
    char* szGBK = new char[len + 1];
    memset(szGBK, 0, len + 1);
    WideCharToMultiByte(CP_ACP, 0, wszGBK, -1, szGBK, len, NULL, NULL);
    string strTemp(szGBK);
    if (wszGBK) delete[] wszGBK;
    if (szGBK) delete[] szGBK;
    return strTemp;
}
#else
#include <iconv.h>

int GbkToUtf8(char *str_str, size_t src_len, char *dst_str, size_t dst_len)
{
    iconv_t cd;
    char **pin = &str_str;
    char **pout = &dst_str;

    cd = iconv_open("utf8", "gbk");
    if (cd == 0)
        return -1;
    memset(dst_str, 0, dst_len);
    if (iconv(cd, pin, &src_len, pout, &dst_len) == -1)
        return -1;
    iconv_close(cd);
    *pout = 0;

    return 0;
}

int Utf8ToGbk(char *src_str, size_t src_len, char *dst_str, size_t dst_len)
{
    iconv_t cd;
    char **pin = &src_str;
    char **pout = &dst_str;

    cd = iconv_open("gbk", "utf8");
    if (cd == 0)
        return -1;
    memset(dst_str, 0, dst_len);
    if (iconv(cd, pin, &src_len, pout, &dst_len) == -1)
        return -1;
    iconv_close(cd);
    *pout = 0;

    return 0;
}

#endif

int main(void)
{
    char *src_str = "葡萄美酒夜光杯";
    cout << "origin string: " << src_str << endl;

#ifdef _WIN32
    // windows default is gbk
    string dst_str = GbkToUtf8(src_str);
    cout << "gbk to utf8: " << dst_str << endl;

    string str_utf8 = Utf8ToGbk(dst_str.c_str());
    cout << "utf8 to gbk: " << str_utf8 << endl;
#else
    // unix default is utf8
    char dst_gbk[1024] = { 0 };
    Utf8ToGbk(src_str, strlen(src_str), dst_gbk, sizeof(dst_gbk));
    cout << "utf8 to gbk: " << dst_gbk << endl;

    char dst_utf8[1024] = { 0 };
    GbkToUtf8(dst_gbk, strlen(dst_gbk), dst_utf8, sizeof(dst_utf8));
    cout << "gbk to utf8: " << dst_utf8 << endl;
#endif

    return 0;
}

优化后的程序

/**
 * @brief
 * 参考自:
 * http://www.voidcn.com/article/p-ockzffzf-bmh.html
 * https://blog.csdn.net/u012234115/article/details/83186386
 *
 * @param src_str
 * @param src_len
 * @param dst_str
 * @param dst_len
 * @return
 */
int GbkToUtf8(const char *src_str, size_t src_len, char *dst_str, size_t dst_len)
{
    /**
     * 源字符串为空，不需要进行转换
     */
    if (src_str[0] == '\0' || src_len == 0)
    {
        return 0;
    }
    /**
     * 目标字符串为空，则无法进行转换
     */
    if (dst_len == 0)
    {
        LOG_ERROR("目标字符串长度为0，无法进行转换");
        return -1;
    }
    //计算由gbk转换为unicode后，unicode编码的长度
    int len = MultiByteToWideChar(CP_ACP, 0, src_str, -1, NULL, 0); //cp_acp指示了转换为unicode编码的编码类型
    if (len <= 0)
    {
        LOG_ERROR("转换失败，长度计算错误");
        return -1;
    }
    else
    {
        std::vector<wchar_t> w_str_(len + 1, 0); // 使用vector，会更加安全高效
        wchar_t *wstr = w_str_.data();
        //ansi到unicode转换
        MultiByteToWideChar(CP_ACP, 0, src_str, -1, wstr, len); //cp_acp指示了转换为unicode编码的编码类型

        // //计算unicode转换为utf8后，utf8编码的长度
        len = WideCharToMultiByte(CP_UTF8, 0, wstr, -1, NULL, 0, NULL, NULL);
        if (len <= 0)
        {
            LOG_ERROR("转换失败，长度计算错误");
            return -1;
        }
        else
        {
//          std::vector<char> str_(len + 1, 0); // 使用vector，会更加安全高效
//          char *str = str_.data();
            if (len + 1 > dst_len)
            {
                LOG_ERROR("长度大于目标字符串数组的长度，信息可能被截断");
                return -1;
            }
            else
            {
                //unicode到utf8转换
                WideCharToMultiByte(CP_UTF8, 0, wstr, -1, dst_str, len, NULL, NULL); //cp_utf8指示了unicode转换为的类型
                return 0;
            }
        }
    }

}

std::string Utf8ToGbk(const char *src_str)
{
    int len = MultiByteToWideChar(CP_UTF8, 0, src_str, -1, NULL, 0);
//  wchar_t* wszGBK = new wchar_t[len + 1];
//  memset(wszGBK, 0, len * 2 + 2);
    std::vector<wchar_t> wszGBK_(len + 1, 0); // 使用vector，会更加安全高效
    wchar_t *wszGBK = wszGBK_.data();

    MultiByteToWideChar(CP_UTF8, 0, src_str, -1, wszGBK, len);
    len = WideCharToMultiByte(CP_ACP, 0, wszGBK, -1, NULL, 0, NULL, NULL);

//  char* szGBK = new char[len + 1];
//  memset(szGBK, 0, len + 1);
    std::vector<char> szGBK_(len + 1, 0); // 使用vector，会更加安全高效
    char *szGBK = szGBK_.data();

    WideCharToMultiByte(CP_ACP, 0, wszGBK, -1, szGBK, len, NULL, NULL);
    std::string strTemp(szGBK);

//  if (wszGBK) delete[] wszGBK;
//  if (szGBK) delete[] szGBK;
    return strTemp;
}
}
#else
#include <iconv.h>

namespace AMUST
{
/**
 * @brief 将GBK转换为UTF8
 *
 * @param str_str
 * @param src_len
 * @param dst_str
 * @param dst_len
 * @return
 */
static int GbkToUtf8(char *str_str, size_t src_len, char *dst_str, size_t dst_len)
{
    /**
     * 源字符串为空，不需要进行转换
     */
    if (src_str[0] == '\0' || src_len == 0)
    {
        return 0;
    }
    /**
     * 目标字符串为空，则无法进行转换
     */
    if (dst_len == 0)
    {
        return -1;
    }
    iconv_t cd;
    char **pin = &str_str;
    char **pout = &dst_str;

    cd = iconv_open("utf8", "gbk");
    if (cd == 0) // 分配失败了
    {
        return -1;
    }
    SCOPE_EXIT { iconv_close(cd);}; // 保证资源得到释放
    memset(dst_str, 0, dst_len);
    if (iconv(cd, pin, &src_len, pout, &dst_len) == -1)
    {
        // 转换失败了
        return -1;
    }

    *pout = 0;

    return 0;
}

static int Utf8ToGbk(char *src_str, size_t src_len, char *dst_str, size_t dst_len)
{
    /**
     * 源字符串为空，不需要进行转换
     */
    if (src_str[0] == '\0' || src_len == 0)
    {
        return 0;
    }
    /**
     * 目标字符串为空，则无法进行转换
     */
    if (dst_len == 0)
    {
        return -1;
    }
    iconv_t cd;
    char **pin = &src_str;
    char **pout = &dst_str;

    cd = iconv_open("gbk", "utf8");
    if (cd == 0)
    {
        return -1;
    }
    SCOPE_EXIT { iconv_close(cd);}; // 保证资源得到释放

    memset(dst_str, 0, dst_len);
    if (iconv(cd, pin, &src_len, pout, &dst_len) == -1)
    {
        return -1;
    }
    *pout = 0;

    return 0;
}

Windows版的注释是参考的:

http://www.voidcn.com/article/p-ockzffzf-bmh.html