问题描述
我想让这个字符串的主机名部分是可变的..目前,它只修复了这个 URL:
_T(" --url=http://www.myurl.com/--out=c:\current.png");
我想做这样的东西,所以网址是可变的..
_T(" --url=http://www." + myurl + "/--out=c:\current.png");
更新.以下是我最近的尝试:
CString one = _T(" --url=http://www.");CString 二(url->bstrVal);CString 三 = _T("/--out=c:\current.png");CString full = 一+二+三;外壳执行(0,_T("open"),//要执行的操作_T("c:\IECapt"),//应用名称_T(full),//附加参数0,//默认目录SW_HIDE);
错误是:Error 1 error C2065: 'Lfull' : undeclared identifier c: est.cpp
它不起作用,因为 _T()
宏仅适用于 constant 字符串文字._T()
的定义如下所示:
#ifdef UNICODE#define _T(str) L##str#别的#define _T(str) str
由于您显然是在 Unicode 模式下编译,_T(full)
扩展为 Lfull
,这显然不是您想要的.
在您的情况下,只需传入 full
而不使用 _T()
宏,因为 CString
定义了一个转换运算符到 constwchar_t*
在 Unicode 模式下,const char*
在非 Unicode 模式下.
ShellExecute(0, _T("open"), _T("c:\IECapt"), full, 0, SW_HIDE);
<小时>
请注意,标准 C++ 还提供了一个 std::string
类型和一个 std::wstring
类型,它们的作用与 CString
的作用差不多,因此字符串操作实际上不需要 MFC.std::string
确实不提供转换运算符,但确实通过c_str()
提供对底层 C 样式字符串的访问.>
I want to make the hostname part of this string to be variable.. Currently, it is only fix to this URL:
_T(" --url=http://www.myurl.com/ --out=c:\current.png");
I want to make something like this, so the URL is changeable..
_T(" --url=http://www." + myurl + "/ --out=c:\current.png");
update. Below is my latest attempt:
CString one = _T(" --url=http://www.");
CString two(url->bstrVal);
CString three = _T("/ --out=c:\current.png");
CString full = one + two + three;
ShellExecute(0,
_T("open"), // Operation to perform
_T("c:\IECapt"), // Application name
_T(full),// Additional parameters
0, // Default directory
SW_HIDE);
The error is : Error 1 error C2065: 'Lfull' : undeclared identifier c: est.cpp
It doesn't work because the _T()
macro works only with constant string literals. The definition for _T()
looks something like this:
#ifdef UNICODE
#define _T(str) L##str
#else
#define _T(str) str
Since you're apparently compiling in Unicode mode, _T(full)
expands to Lfull
, which is obviously not what you want.
In your case, just pass in full
without the _T()
macro since CString
defines a conversion operator to a const wchar_t*
in Unicode mode, and const char*
in non-Unicode mode.
ShellExecute(0, _T("open"), _T("c:\IECapt"), full, 0, SW_HIDE);
Note that standard C++ also provides a std::string
type and a std::wstring
type which does pretty much what CString
does, so MFC isn't actually required for string manipulation. std::string
does not provide a conversion operator, but does provide access to the underlying C-style string via c_str()
.
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