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I have written the following statements: 

   CString strResult;
   std::string errorReason("no this item");
   strResult.Format("the error reason is: %s", errorReason);

It seems that it could not format the std::string object correctly; However, if I just replace std::string as CStirng, then strResult could format correctly.

Why va_arg could support CStirng, instead of std::string?

Thanks

CloudyMarble
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xinsong001
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1 Answers1

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Unlike CString, std::string doesn't provide an implicit conversion to const char* (for good reasons) and, what is more important in this case, the binary layout of std::string may not be compatible with const char*. You should use errorReason.c_str() instead.

Community
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vitaut
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