视觉c++运算符 += 不明确
CString szMsg;
//Other non related code
//stOrderInfo.bstrOrderNum is defined as a _bstr_t
szMsg += ", Order: " + stOrderInfo.bstrOrderNum;
我将上述内容从 VS 6.0 转换为 VS2k10，并且收到以下错误（在 VS 6.0 中编译）：
error C2593: 'operator +=' is ambiguous
这到底是什么意思以及如何修复它？
CString szMsg;
//Other non related code
//stOrderInfo.bstrOrderNum is defined as a _bstr_t
szMsg += ", Order: " + stOrderInfo.bstrOrderNum;
I'm converting the above from VS 6.0 to VS2k10 and I'm getting the following error (compiles in VS 6.0):
error C2593: 'operator +=' is ambiguous
What exactly does this mean and how can I fix it?
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因为您已经硬编码了 ", Order: " 编译器很难决定它应该是什么类型。
明显的类型应该是
CString，但它可能会尝试将其转换为其他字符串类型，并向其中添加数字。因此它可能无法确定它是 CString 还是其他字符串类型。因此它无法决定您要添加到 szMsg 中的类型。
您可以只使用类型转换：
在字符串类型之间转换：
如何：在各种字符串类型之间进行转换
Because you've hard-coded ", Order: " the compiler is having a hard time to decide which type it should be.
The obvious type should be
CString, but it might try to make it to some other string type, and add the number to it.So it probably can't decide if it's a
CStringor another string type. So it can't decide what type you're adding to szMsg.You could just use a type cast:
Cast between string types:
How to: Convert Between Various String Types
这意味着编译器无法选择对 BSTR + 字符连接使用哪个 + 运算。存在三种类型不匹配：CString、_bstr_t 和 char。
尝试将所有三个操作数统一为单一类型，例如 CString
This means that compiler cannot choose which + operation to use for BSTR + char concatenations. You have a mismatch of three types: CString, _bstr_t, and char.
Try to unify all three operands to a single type, e.g. to CString
已知
CString::operator+=的实现在 Visual Studio 2010 中发生了变化。例如，在以前的版本中，它可以正常处理嵌入的空字符，就像operator+一直在做的那样，但新版本没有。所以可能和这个有关。编辑
有关此主题的讨论的链接：
http://social.msdn.microsoft.com/Forums/en-US/vcmfcatl/thread/c5d7f383-da80-4776-b9b8-a6065839bd87
The implementation of
CString::operator+=is known to have changed in Visual Studio 2010. For example in previous versions it handled embedded null characters OK, just likeoperator+keeps doing, but the new version doesn't. So it might be related to this.EDIT
Link to discussion on this topic:
http://social.msdn.microsoft.com/Forums/en-US/vcmfcatl/thread/c5d7f383-da80-4776-b9b8-a6065839bd87
最好使用
CString::AppendFormat。但请确保您传递正确的格式说明符。Better use
CString::AppendFormat. But ensure you pass correct format-specifier.