上面有很多好的建议,适用于大多数情况。在我的情况下,我最终想要从资源中加载字符串,并尽可能地让字符串资源与.NET String.Format保持接近,所以我自己写了一个。在查看上面的一些实现以获取想法后,得出的实现非常简短和易于理解。
有一个名为String的类,在我的情况下它派生自Microsoft的CString,但它可以派生自任何字符串类。还有一个名为StringArg的类,它的工作是接受任何参数类型并将其转换为字符串(它模仿.NET中的ToString方法)。如果需要为新对象进行ToString操作,只需添加另一个构造函数。该构造函数允许为非默认格式指定符提供printf样式的格式说明符。
然后,String类接受源字符串的字符串表ID、若干个StringArg参数和最后一个可选HINSTANCE(我使用了很多DLL,任何一个都可以托管字符串表,因此这允许我传入它,或者默认使用特定于DLL的HINSTANCE)。
用法示例:
dlg.m_prompt = String(1417)
MessageBox(String(1532, m_username))
目前它只接受一个字符串ID作为输入,但是添加一个输入字符串而不是字符串ID将非常简单:
CString s = String.Format("Hi {0}, you are {1} years old in Hexidecimal", m_userName, StringArg(m_age, "%0X"));
现在让我们来看一下StringArg类,它可以对变量执行相当于ToString的操作:
class StringArg
{
StringArg();
StringArg(const StringArg&);
StringArg& operator=(const StringArg&);
public:
StringArg(LPCWSTR val);
StringArg(const CString& val);
StringArg(int val, LPCWSTR formatSpec = NULL);
StringArg(size_t val, LPCWSTR formatSpec = NULL);
StringArg(WORD val, LPCWSTR formatSpec = NULL);
StringArg(DWORD val, LPCWSTR formatSpec = NULL);
StringArg(__int64 val, LPCWSTR formatSpec = NULL);
StringArg(double val, LPCWSTR formatSpec = NULL);
CString ToString() const;
private:
CString m_strVal;
};
extern HINSTANCE GetModuleHInst();
对于String类,有许多成员函数和构造函数,最多可以接受10个参数。这些最终调用CentralFormat执行真正的工作。
class String : public CString
{
public:
String() { }
String(WORD stringTableID, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, hInst); }
String(WORD stringTableID, const StringArg& arg1, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, hInst); }
String(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, arg2, hInst); }
String(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, arg2, arg3, hInst); }
String(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, arg2, arg3, arg4, hInst); }
String(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, arg2, arg3, arg4, arg5, hInst); }
String(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, arg2, arg3, arg4, arg5, arg6, hInst); }
String(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, arg2, arg3, arg4, arg5, arg6, arg7, hInst); }
String(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, const StringArg& arg8, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, hInst); }
String(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, const StringArg& arg8, const StringArg& arg9, HINSTANCE hInst = GetModuleHInst()) { Format(stringTableID, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9, hInst); }
CString& Format(WORD stringTableID, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, const StringArg& arg8, HINSTANCE hInst = GetModuleHInst());
CString& Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, const StringArg& arg8, const StringArg& arg9, HINSTANCE hInst = GetModuleHInst());
private:
void CentralFormat(WORD stringTableID, std::vector<const StringArg*>& args, HINSTANCE hInst);
};
最后,这是实现的代码(希望在StackOverflow上发布这么多内容没有问题,虽然大部分非常简单):
StringArg::StringArg(LPCWSTR val)
{
m_strVal = val;
}
StringArg::StringArg(const CString& val)
{
m_strVal = (LPCWSTR)val;
}
StringArg::StringArg(int val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%d";
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(size_t val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%u";
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(WORD val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%u";
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(DWORD val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%u";
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(__int64 val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%I64d";
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(double val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%f";
m_strVal.Format(formatSpec, val);
}
CString StringArg::ToString() const
{
return m_strVal;
}
void String::CentralFormat(WORD stringTableID, std::vector<const StringArg*>& args, HINSTANCE hInst)
{
size_t argsCount = args.size();
_ASSERT(argsCount < 10);
CString tmp;
HINSTANCE hOld = AfxGetResourceHandle();
AfxSetResourceHandle(hInst);
BOOL b = tmp.LoadString(stringTableID);
AfxSetResourceHandle(hOld);
if(FALSE == b)
{
#ifdef _DEBUG
CString s;
s.Format(L"StringID %d could not be found! %s", stringTableID, hInst == ghCommonHInst ? L"CommonHInst was passed in" : L"CommonHInst was NOT passed in");
::MessageBeep(MB_ICONHAND);
::MessageBeep(MB_ICONEXCLAMATION);
::MessageBeep(MB_ICONHAND);
_ASSERT(0);
::MessageBox(NULL, s, L"DEBUG Error - Inform Development", MB_ICONSTOP | MB_OK | MB_SERVICE_NOTIFICATION);
}
#endif
CString::Format(L"(???+%d)", stringTableID);
return;
}
if(0 == argsCount)
{
CString::operator=(tmp);
return;
}
GetBuffer(tmp.GetLength() * 3);
ReleaseBuffer(0);
LPCWSTR pStr = tmp;
while(L'\0' != *pStr)
{
bool bSkip = false;
if(L'{' == *pStr)
{
if(wcschr(L"0123456789", *(pStr + 1)))
{
if(L'}' == *(pStr + 2))
{
bSkip = true;
size_t index = *(pStr + 1) - L'0';
_ASSERT(index < argsCount);
_ASSERT(index >= 0);
if((index >= 0) && (index < argsCount))
CString::operator+=(args[index]->ToString());
else
{
CString msg;
msg.Format(L"(??-%d)", index);
CString::operator+=(msg);
}
pStr += 2;
}
}
}
if(false == bSkip)
CString::operator+=(*pStr);
pStr++;
}
}
CString& String::Format(WORD stringTableID, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
args.push_back(&arg2);
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
args.push_back(&arg2);
args.push_back(&arg3);
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
args.push_back(&arg2);
args.push_back(&arg3);
args.push_back(&arg4);
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
args.push_back(&arg2);
args.push_back(&arg3);
args.push_back(&arg4);
args.push_back(&arg5);
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
args.push_back(&arg2);
args.push_back(&arg3);
args.push_back(&arg4);
args.push_back(&arg5);
args.push_back(&arg6);
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
args.push_back(&arg2);
args.push_back(&arg3);
args.push_back(&arg4);
args.push_back(&arg5);
args.push_back(&arg6);
args.push_back(&arg7);
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, const StringArg& arg8, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
args.push_back(&arg2);
args.push_back(&arg3);
args.push_back(&arg4);
args.push_back(&arg5);
args.push_back(&arg6);
args.push_back(&arg7);
args.push_back(&arg8);
CentralFormat(stringTableID, args, hInst);
return *this;
}
CString& String::Format(WORD stringTableID, const StringArg& arg1, const StringArg& arg2, const StringArg& arg3, const StringArg& arg4, const StringArg& arg5, const StringArg& arg6, const StringArg& arg7, const StringArg& arg8, const StringArg& arg9, HINSTANCE hInst)
{
std::vector<const StringArg*> args;
args.push_back(&arg1);
args.push_back(&arg2);
args.push_back(&arg3);
args.push_back(&arg4);
args.push_back(&arg5);
args.push_back(&arg6);
args.push_back(&arg7);
args.push_back(&arg8);
args.push_back(&arg9);
CentralFormat(stringTableID, args, hInst);
return *this;
}