String.Format for C ++ [英] String.Format for C++
问题描述
寻找一个像.NET的String.Format这样的函数的C ++实现。显然有printf和它的品种，但我正在寻找位置的东西，如：
Looking for an implementation for C++ of a function like .NET's String.Format. Obviously there is printf and it's varieties, but I'm looking for something that is positional as in:
String.Format {0}，您是
{1}岁，感觉如何是
{1}？，姓名，年龄）;
String.Format("Hi there {0}. You are {1} years old. How does it feel to be {1}?", name, age);
这是需要的，因为我们将尝试让我们的应用程序本地化变得更容易，并且让译员{0}和{1}在句子中的任何位置放置要容易得多给它们一个％s，％d，％d，它们必须按照它们的翻译顺序排列。
This is needed because we're going to try and make it easier to localize our app, and giving the translators {0} and {1} to position anywhere in the sentence is much easier than giving them a %s, %d, %d which must be positioned in that order in their translation.
我假设搜索和替换变量输入（va_start，va_end，
I suppose search and replace with variable inputs (va_start, va_end, etc) is what I'll end up building, but if there is already a solid solution, that would be preferrable.
感谢：）
推荐答案
上面的许多好的建议在大多数情况下都可行。在我的情况下，我最终想从一个资源加载字符串，并保持字符串资源尽可能接近.NET String.Format，所以我滚动自己的。在看了一些上面的实现之后，最终的实现是相当短和容易。
Lots of good recommendations above that would work in most situations. In my case, I ultimately wanted to load strings from a resource, AND keep the string resources as close to .NET String.Format as I could, so I rolled my own. After looking at some of the implementations above for ideas, the resulting implementation was quite short and easy.
有一个类String，在我的情况下从Microsoft的CString派生，但它可以派生自任何字符串类。还有一个类StringArg - 它的任务是采取任何参数类型并将其转换为字符串（即它模仿.NET中的ToString）。如果一个新对象需要ToString，你只需要添加另一个构造函数。
There is a class String, which in my case derives from Microsoft's CString, but it could derive from about any string class. There is also a class StringArg -- it's job is to take any parameter type and turn it into a string (ie it mimics ToString in .NET). If a new object needs to be ToString'd, you just add another constructor. The constructor allows a printf-style format specifier for non-default formatting.
String类接受源字符串的字符串表ID，StringArg参数的数量，和最后一个可选的HINSTANCE（我使用大量的DLL，任何一个可以主机的字符串表，所以这允许我传递它，或使用DLL特定的HINSTANCE默认情况下）。
The String class then accepts a string table ID for the source string, a number of StringArg parameters, and finally an optional HINSTANCE (I use lots of DLLs, any of which could host the string table, so this allowed me to pass it in, or use a DLL-specific HINSTANCE by default).
使用示例：
dlg.m_prompt = String(1417); //"Welcome to Stackoverflow!"
MessageBox(String(1532, m_username)); //"Hi {0}"
因为它只是输入一个字符串ID ，但是添加一个输入字符串而不是字符串ID是很简单的：
As it is, it only takes a string ID for an input, but it would be trivial to add an input string instead of a string ID:
CString s = String.Format("Hi {0}, you are {1} years old in Hexidecimal", m_userName, StringArg(m_age, "%0X"));
现在，对于在变量上等效于ToString的StringArg类：
Now for the StringArg class which does the equivalent of ToString on variables:
class StringArg
{
StringArg(); //not implemented
StringArg(const StringArg&); //not implemented
StringArg& operator=(const StringArg&); //not implemented
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(); //every DLL implements this for getting it's own HINSTANCE -- scenarios with a single resource DLL wouldn't need this
对于String类，有一堆成员函数和构造函数，最多可以使用10个参数。这些最终调用CentralFormat来完成真正的工作。
For the String class, there are a bunch of member functions and constructors that take up to 10 arguments. These ultimately call CentralFormat which does the real work.
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，实现（希望可以在StackOverflow上发布，非常简单）：
Finally, the implementation (hopefully it's OK to post this much on StackOverflow, although the bulk of it is very simple):
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"; //GLOK
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(size_t val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%u"; //GLOK
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(WORD val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%u"; //GLOK
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(DWORD val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%u"; //GLOK
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(__int64 val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%I64d"; //GLOK
m_strVal.Format(formatSpec, val);
}
StringArg::StringArg(double val, LPCWSTR formatSpec)
{
if(NULL == formatSpec)
formatSpec = L"%f"; //GLOK
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); //code below assumes a single character position indicator
CString tmp;
HINSTANCE hOld = AfxGetResourceHandle();
AfxSetResourceHandle(hInst);
BOOL b = tmp.LoadString(stringTableID);
AfxSetResourceHandle(hOld);
if(FALSE == b)
{
#ifdef _DEBUG
//missing string resource, or more likely a bad stringID was used -- tell someone!!
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"); //GLOK
::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); //GLOK
}
#endif //_DEBUG
CString::Format(L"(???+%d)", stringTableID); //GLOK
return;
}
//check for the degenerate case
if(0 == argsCount)
{
CString::operator=(tmp);
return;
}
GetBuffer(tmp.GetLength() * 3); //pre-allocate space
ReleaseBuffer(0);
LPCWSTR pStr = tmp;
while(L'\0' != *pStr)
{
bool bSkip = false;
if(L'{' == *pStr)
{
//is this an incoming string position?
//we only support 10 args, so the next char must be a number
if(wcschr(L"0123456789", *(pStr + 1))) //GLOK
{
if(L'}' == *(pStr + 2)) //and closing brace?
{
bSkip = true;
//this is a replacement
size_t index = *(pStr + 1) - L'0';
_ASSERT(index < argsCount);
_ASSERT(index >= 0);
if((index >= 0) && (index < argsCount))
CString::operator+=(args[index]->ToString());
else
{
//bad positional index
CString msg;
msg.Format(L"(??-%d)", index); //GLOK
CString::operator+=(msg);
}
pStr += 2; //get past the two extra characters that we skipped ahead and peeked at
}
}
}
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;
}
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