CString－>TCHAR*的转化可以用函数GetBuff()
函数原型为：LPTSTR GetBuffer( int nMinBufLength );
CString str("CString");
TCHAR* szMsg = new TCHAR[100];
//其参数为CString字符串的长度
szMsg = str.GetBuffer(str.GetLength());
str.ReleaseBuffer();
delete []szMsg;
szMsg = NULL;
TCHAR*－>CString的转化
TCHAR szTchar[18] = L"TCHAR";
CString str;
str.Format(_T("%s"),szTchar);
CString和string的互相转换
CString->std::string 例子：
CString strMfc="test";
std::string strStl;
strStl=strMfc.GetBuffer(0);
std::string->CString 例子：
CString strMfc；
std::string strStl="test";
strMfc=strStl.c_str();
对有关数据类型转换的整理
int i = 100;
long l = 2001;
float f=300.2;
double d=12345.119;
char username[]="程佩君";
char temp[200];
char *buf;
CString str;
_variant_t v1;
_bstr_t v2;
一、其它数据类型转换为字符串
- 短整型(int)
itoa(i,temp,10);///将i转换为字符串放入temp中,最后一个数字表示十进制
itoa(i,temp,2); ///按二进制方式转换 - 长整型(long)
ltoa(l,temp,10); - 浮点数(float,double)
用fcvt可以完成转换,这是MSDN中的例子:
int decimal, sign;
char *buffer;
double source = 3.1415926535;
buffer = _fcvt( source, 7, &decimal, &sign );
运行结果:source: 3.1415926535 buffer: '31415927' decimal: 1 sign: 0
decimal表示小数点的位置,sign表示符号:0为正数，1为负数 - CString变量
str = "2008北京奥运";
buf = (LPSTR)(LPCTSTR)str; - BSTR变量
BSTR bstrValue = ::SysAllocString(L"程序员");
char * buf = _com_util::ConvertBSTRToString(bstrValue);
SysFreeString(bstrValue);
AfxMessageBox(buf);
delete(buf); - CComBSTR变量
CComBSTR bstrVar("test");
char *buf = _com_util::ConvertBSTRToString(bstrVar.m_str);
AfxMessageBox(buf);
delete(buf); - _bstr_t变量
_bstr_t类型是对BSTR的封装，因为已经重载了=操作符，所以很容易使用
_bstr_t bstrVar("test");
const char *buf = bstrVar;///不要修改buf中的内容
AfxMessageBox(buf); - 通用方法(针对非COM数据类型)
用sprintf完成转换char buffer[200]; char c = '1'; int i = 35; long j = 1000; float f = 1.7320534f; sprintf( buffer, "%c",c); sprintf( buffer, "%d",i); sprintf( buffer, "%d",j); sprintf( buffer, "%f",f);
二、字符串转换为其它数据类型
strcpy(temp,"123");
- 短整型(int)
i = atoi(temp); - 长整型(long)
l = atol(temp); - 浮点(double)
d = atof(temp); - CString变量
CString name = temp; - BSTR变量
BSTR bstrValue = ::SysAllocString(L"程序员");
...///完成对bstrValue的使用
SysFreeString(bstrValue); - CComBSTR变量
CComBSTR类型变量可以直接赋值
CComBSTR bstrVar1("test");
CComBSTR bstrVar2(temp); - _bstr_t变量
_bstr_t类型的变量可以直接赋值
_bstr_t bstrVar1("test");
_bstr_t bstrVar2(temp);
三、其它数据类型转换到CString
使用CString的成员函数Format来转换,例如:
- 整数(int)
str.Format("%d",i); - 浮点数(float)
str.Format("%f",i); - 字符串指针(char *)等已经被CString构造函数支持的数据类型可以直接赋值
str = username; - 对于Format所不支持的数据类型，可以通过上面所说的关于其它数据类型转化到char *的方法先转到char *，然后赋值给CString变量。
四、BSTR、_bstr_t与CComBSTR
- CComBSTR 是ATL对BSTR的封装，_bstr_t是C++对BSTR的封装,BSTR是32位指针,但并不直接指向字串的缓冲区。
char *转换到BSTR可以这样:
BSTR b=_com_util::ConvertStringToBSTR("数据");///使用前需要加上comutil.h和comsupp.lib
SysFreeString(bstrValue);
反之可以使用
char *p=_com_util::ConvertBSTRToString(b);
delete p;
具体可以参考一，二段落里的具体说明。
CComBSTR与_bstr_t对大量的操作符进行了重载，可以直接进行=,!=,==等操作，所以使用非常方便。
特别是_bstr_t,建议大家使用它。
五、VARIANT 、_variant_t 与 COleVariant
- VARIANT的结构可以参考头文件VC98\Include\OAIDL.H中关于结构体tagVARIANT的定义。
对于VARIANT变量的赋值：首先给vt成员赋值，指明数据类型，再对联合结构中相同数据类型的变量赋值，举个例子：
VARIANT va;
int a=2001;
va.vt=VT_I4;///指明整型数据
va.lVal=a; ///赋值 - _variant_t是VARIANT的封装类，其赋值可以使用强制类型转换，其构造函数会自动处理这些数据类型。
使用时需加上#include <comdef.h>
例如：
long l=222;
ing i=100;
_variant_t lVal(l);
lVal = (long)i;
COleVariant的使用与_variant_t的方法基本一样，请参考如下例子：
COleVariant v3 = "字符串", v4 = (long)1999;
CString str =(BSTR)v3.pbstrVal;
long i = v4.lVal;
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////-
本主题演示如何将各种 C++ 字符串类型转换为其他字符串。可以转换的字符串类型包括 char *、wchar_t*、_bstr_t、CComBSTR、CString、basic_string 和 System.String。在所有情况下，在将字符串转换为新类型时，都会创建字符串的副本。对新字符串进行的任何更改都不会影响原始字符串，反之亦然。
从 char * 转换
示例
说明
此示例演示如何从 char * 转换为上面列出的其他字符串类型。
// convert_from_char.cpp // compile with /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { char *orig = "Hello, World!"; cout << orig << " (char *)" << endl; // Convert to a wchar_t* size_t origsize = strlen(orig) + 1; const size_t newsize = 100; size_t convertedChars = 0; wchar_t wcstring[newsize]; mbstowcs_s(&convertedChars, wcstring, origsize, orig, _TRUNCATE); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(orig); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring(orig); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string string basicstring(orig); basicstring += " (basic_string)"; cout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }输出
Hello, World! (char *) Hello, World! (wchar_t *) Hello, World! (_bstr_t) Hello, World! (CComBSTR) Hello, World! (CString) Hello, World! (basic_string) Hello, World! (System::String)
从 wchar_t * 转换
示例
说明
此示例演示如何从 wchar_t * 转换为上面列出的其他字符串类型。
// convert_from_wchar_t.cpp // compile with /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { wchar_t *orig = L"Hello, World!"; wcout << orig << L" (wchar_t *)" << endl; // Convert to a char* size_t origsize = wcslen(orig) + 1; const size_t newsize = 100; size_t convertedChars = 0; char nstring[newsize]; wcstombs_s(&convertedChars, nstring, origsize, orig, _TRUNCATE); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(orig); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring(orig); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string wstring basicstring(orig); basicstring += L" (basic_string)"; wcout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }输出
Hello, World! (wchar_t *) Hello, World! (char *) Hello, World! (_bstr_t) Hello, World! (CComBSTR) Hello, World! (CString) Hello, World! (basic_string) Hello, World! (System::String)
从 _bstr_t 转换
示例
说明
此示例演示如何从 _bstr_t 转换为上面列出的其他字符串类型。
// convert_from_bstr_t.cpp // compile with /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { _bstr_t orig("Hello, World!"); wcout << orig << " (_bstr_t)" << endl; // Convert to a char* const size_t newsize = 100; char nstring[newsize]; strcpy_s(nstring, (char *)orig); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* wchar_t wcstring[newsize]; wcscpy_s(wcstring, (wchar_t *)orig); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a CComBSTR CComBSTR ccombstr((char *)orig); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring((char *)orig); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string string basicstring((char *)orig); basicstring += " (basic_string)"; cout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String((char *)orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }输出
Hello, World! (_bstr_t) Hello, World! (char *) Hello, World! (wchar_t *) Hello, World! (CComBSTR) Hello, World! (CString) Hello, World! (basic_string) Hello, World! (System::String)
从 CComBSTR 转换
示例
说明
此示例演示如何从 CComBSTR 转换为上面列出的其他字符串类型。
// convert_from_ccombstr.cpp // compile with /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" #include "vcclr.h" using namespace std; using namespace System; using namespace System::Runtime::InteropServices; int main() { CComBSTR orig("Hello, World!"); CW2A printstr(orig); cout << printstr << " (CComBSTR)" << endl; // Convert to a char* const size_t newsize = 100; char nstring[newsize]; CW2A tmpstr1(orig); strcpy_s(nstring, tmpstr1); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* wchar_t wcstring[newsize]; wcscpy_s(wcstring, orig); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CString CString cstring(orig); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string wstring basicstring(orig); basicstring += L" (basic_string)"; wcout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }输出
Hello, World! (CComBSTR) Hello, World! (char *) Hello, World! (wchar_t *) Hello, World! (_bstr_t) Hello, World! (CString) Hello, World! (basic_string) Hello, World! (System::String)
从 CString 转换
示例
说明
此示例演示如何从 CString 转换为上面列出的其他字符串类型。
// convert_from_cstring.cpp // compile with /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { CString orig("Hello, World!"); wcout << orig << " (CString)" << endl; // Convert to a char* const size_t newsize = 100; char nstring[newsize]; strcpy_s(nstring, orig); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* // You must first convert to a char * for this to work. size_t origsize = strlen(orig) + 1; size_t convertedChars = 0; wchar_t wcstring[newsize]; mbstowcs_s(&convertedChars, wcstring, origsize, orig, _TRUNCATE); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(orig); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a basic_string string basicstring(orig); basicstring += " (basic_string)"; cout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }输出
Hello, World! (CString) Hello, World! (char *) Hello, World! (wchar_t *) Hello, World! (_bstr_t) Hello, World! (CComBSTR) Hello, World! (basic_string) Hello, World! (System::String)
从 basic_string 转换
示例
说明
此示例演示如何从 basic_string 转换为上面列出的其他字符串类型。
// convert_from_basic_string.cpp // compile with /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { string orig("Hello, World!"); cout << orig << " (basic_string)" << endl; // Convert to a char* const size_t newsize = 100; char nstring[newsize]; strcpy_s(nstring, orig.c_str()); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* // You must first convert to a char * for this to work. size_t origsize = strlen(orig.c_str()) + 1; size_t convertedChars = 0; wchar_t wcstring[newsize]; mbstowcs_s(&convertedChars, wcstring, origsize, orig.c_str(), _TRUNCATE); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig.c_str()); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(orig.c_str()); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring(orig.c_str()); cstring += " (CString)"; cout << cstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig.c_str()); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }输出
Hello, World! (basic_string) Hello, World! (char *) Hello, World! (wchar_t *) Hello, World! (_bstr_t) Hello, World! (CComBSTR) Hello, World! (CString) Hello, World! (System::String)
从 System::String 转换
示例
说明
此示例演示如何从 System.String 转换为上面列出的其他字符串类型。
// convert_from_system_string.cpp // compile with /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" #include "vcclr.h" using namespace std; using namespace System; using namespace System::Runtime::InteropServices; int main() { String ^orig = gcnew String("Hello, World!"); Console::WriteLine("{0} (System::String)", orig); pin_ptr<const wchar_t> wch = PtrToStringChars(orig); // Convert to a char* size_t origsize = wcslen(wch) + 1; const size_t newsize = 100; size_t convertedChars = 0; char nstring[newsize]; wcstombs_s(&convertedChars, nstring, origsize, wch, _TRUNCATE); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* wchar_t wcstring[newsize]; wcscpy_s(wcstring, wch); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(wch); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(wch); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring(wch); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string wstring basicstring(wch); basicstring += L" (basic_string)"; wcout << basicstring << endl; delete orig; }输出
Hello, World! (System::String) Hello, World! (char *) Hello, World! (wchar_t *) Hello, World! (_bstr_t) Hello, World! (CComBSTR) Hello, World! (CString) Hello, World! (basic_string)