C++ string 、char 、char *、wstring、wchar_t * 、wchar_t 之间的转换

原博文链接：http://www.aobosir.com/blog/2016/12/16/cpp-convert-string-wstring-char-wchar_t-pointer/

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char 与 wchar_t 之间的转换

#include 
#include 

int main(void)
{
    char c = 'a';
    std::cout << c << std::endl;
    //char -> wchar_t
    wchar_t wc = (wchar_t)c;
    std::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << wc << std::endl;
    //wchar_t -> char
    char c_ = (char)wc;
    std::cout << c_ << std::endl;

    system("pause");
    return 0;
}

输出：

a
U+0061
a
请按任意键继续. . .

Unicode编码表：A-Z,a-z,0-9的unicode编码表

string 与 wstring 之间的转换

#include 
#include 
#include 

int main(void)
{
    std::string str = "HelloWorld";
    std::cout << str << std::endl;
    //string -> wstring
    std::wstring wstr;
    wstr.assign(str.begin(), str.end());
    // std::cout << wstr.c_str() << std::endl; //error 这样是打印不出来的
    //std::cout << wstr.c_str() << std::endl; //error 编译不报错，但是它打印的是wstr第一个字符的地址
    //打印 success
    std::cout << "Unicode is ";
    for(int i=0; istd::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << wstr[i] << " ";
    }
    std::cout << std::endl;
    //打印 end

    //wstring -> string
    std::string str_;
    str_.assign(wstr.begin(), wstr.end());
    std::cout << str_ << std::endl;

    system("pause");
    return 0;
}

输出：

HelloWorld
Unicode is U+0048 U+0065 U+006c U+006c U+006f U+0057 U+006f U+0072 U+006c U+0064
HelloWorld
请按任意键继续. . .

char * 与 string 之间的转换

#include 
#include 

int main(void)
{
    std::string str = "HelloWorld";
    //string -> char *
    char * cstr = (char *)str.c_str();
    std::cout << cstr << std::endl;
    //char * -> string
    std::string str_ = cstr;
    std::cout << str_ << std::endl;

    system("pause");
    return 0;
}

输出：

HelloWorld
HelloWorld
请按任意键继续. . .

char * 与 wchar_t * 之间的转换

#include 
#include 

int main(void)
{
    char * cstr = "HelloWorld";
    std::cout << cstr << std::endl;

    // char * -> wchar_t *
    //wchar_t * wcstr = (wchar_t *)cstr; //error
    //success
    size_t len = strlen(cstr) + 1;
    size_t converted = 0;
    wchar_t *wcstr;
    wcstr=(wchar_t*)malloc(len*sizeof(wchar_t));
    mbstowcs_s(&converted, wcstr, len, cstr, _TRUNCATE);

    //打印
    wchar_t * temp = wcstr;
    int i = 0;
    std::cout << "Unicode is ";
    while(temp[i]!='\0'){
        std::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << temp[i] << " ";
        i++;
    }
    std::cout << std::endl;
    //打印 end

    std::cout << "------------------" << std::endl;
    //-------------------------------------------------

    wchar_t * wcstr_ = L"HelloWorld";
    //打印
    wchar_t * temp_ = wcstr_;
    int i_ = 0;
    std::cout << "Unicode is ";
    while(temp_[i_]!='\0'){
        std::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << temp_[i_] << " ";
        i_++;
    }
    std::cout << std::endl;
    //打印 end

    //wchar_t * -> char *
    size_t len_ = wcslen(wcstr_) + 1;
    size_t converted_ = 0;
    char * cstr_;
    cstr_ = (char*)malloc(len*sizeof(char));
    wcstombs_s(&converted_, cstr_, len_, wcstr_, _TRUNCATE);
    std::cout << cstr_ << std::endl;

    system("pause");
    return 0;
}

输出：

HelloWorld
Unicode is U+0048 U+0065 U+006c U+006c U+006f U+0057 U+006f U+0072 U+006c U+0064
------------------
Unicode is U+0048 U+0065 U+006c U+006c U+006f U+0057 U+006f U+0072 U+006c U+0064
HelloWorld
请按任意键继续. . .

注意：

• cstr、wcstr、cstr_ 是地址变量，使用 std::cout << cstr_ << std::endl;代码打印的值是地址，并不是字符串的值。
• wchar_t * 与 char * 之间的转换，使用wchar_t * wcstr = (wchar_t *)cstr;是错误的。（异想天开）

wchar_t * 与 wstring 之间的转换

#include 
#include 
#include 

int main(void)
{
    std::wstring wstr = L"HelloWorld";
    //打印
    std::cout << "Unicode is ";
    for(int i=0; istd::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << wstr[i] << " ";
    }
    std::cout << std::endl;
    //打印 end
    //wstring -> wchar_t *
    wchar_t * wcstr = (wchar_t *)wstr.c_str();
    //打印
    wchar_t * temp = wcstr;
    int i = 0;
    std::cout << "Unicode is ";
    while(temp[i]!='\0'){
        std::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << temp[i] << " ";
        i++;
    }
    std::cout << std::endl;
    //打印 end
    //wchar_t * -> wstring
    std::wstring wstr_ = wcstr;
    //打印
    std::cout << "Unicode is ";
    for(int i=0; istd::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << wstr_[i] << " ";
    }
    std::cout << std::endl;
    //打印 end

    system("pause");
    return 0;
}

输出：

Unicode is U+0048 U+0065 U+006c U+006c U+006f U+0057 U+006f U+0072 U+006c U+0064
Unicode is U+0048 U+0065 U+006c U+006c U+006f U+0057 U+006f U+0072 U+006c U+0064
Unicode is U+0048 U+0065 U+006c U+006c U+006f U+0057 U+006f U+0072 U+006c U+0064
请按任意键继续. . .

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wchar_t * 与 string 之间的转换

知道了上面的几种转换，我们就可以通过组合它们，来实现，比如：wchar_t * 与 string 之间的转换。

#include 
#include 
#include 

int main(void)
{
    std::wstring wstr = L"HelloWorld";
    wchar_t * wcstr = (wchar_t *)wstr.c_str();
    //打印
    wchar_t * temp = wcstr;
    int i = 0;
    std::cout << "Unicode is ";
    while(temp[i]!='\0'){
        std::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << temp[i] << " ";
        i++;
    }
    std::cout << std::endl;
    //打印 end

    //wchar_t * -> string (wchar_t * -> wstring -> string)
    std::wstring wstr_ = wcstr;
    std::string str;
    str.assign(wstr_.begin(), wstr_.end());
    std::cout << str << std::endl;
    //string -> wchar_t * (string -> wstring -> wchar_t *)
    wstr_.assign(str.begin(), str.end());
    wchar_t * wcstr_ = (wchar_t *)wstr_.c_str();
    //打印
    wchar_t * temp_ = wcstr;
    int i_ = 0;
    std::cout << "Unicode is ";
    while(temp_[i_]!='\0'){
        std::cout << "U+" << std::setw(4) << std::setfill('0') << std::hex << temp_[i_] << " ";
        i_++;
    }
    std::cout << std::endl;
    //打印 end

    system("pause");
    return 0;
}

输出：

Unicode is U+0048 U+0065 U+006c U+006c U+006f U+0057 U+006f U+0072 U+006c U+0064
HelloWorld
Unicode is U+0048 U+0065 U+006c U+006c U+006f U+0057 U+006f U+0072 U+006c U+0064
请按任意键继续. . .

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