带有utf16 char的json字符串无法从'const char [566]'转换为'std :: basic_string< _Elem,_Traits,_Ax>' [英] json string with utf16 char cannot convert from 'const char [566]' to 'std::basic_string<_Elem,_Traits,_Ax>'
问题描述
我有需要测试带有utf16宽字符的字符串的json,但是我收到以下错误消息:
I have json that needs to test a string with a utf16 wide char in it but I get the following error message:
\..\test\TestClass.cpp(617): error C2440: 'initializing' : cannot convert from 'const char [566]' to 'std::basic_string<_Elem,_Traits,_Ax>'
with
2> [
2> _Elem=wchar_t,
2> _Traits=std::char_traits<wchar_t>,
2> _Ax=std::allocator<wchar_t>
2> ]
2> No constructor could take the source type, or constructor overload resolution was ambiguous
这是我的json:
static std::wstring& BAD_JSON5_missingComma_multipleNewlines_Utf16MixedDosAndUnixLineEndings()
{
static std::wstring j =
"{\n" <=VS squigly says error on this line
"\"header\":{\n"
"\"version\":{\"major\":1,\"minor\":0,\"build\":0}\n"
"},\n"
"\"body\":{\n"
"\"string\":{\"type\":\"OurWideStringClass\",\"value\":\"foo\"},\n\n\n\n"
"\"int\":[\n"
"{\"type\":\"string\",\"value\":\"\\u9CE5\"},\n"
"{\"type\":\"Int\",\"value\":5678}\n"
"],\n"
"\"double\":{\"type\":\"Double\",\"value\":12.34},\n"
"\"path1\":[\n"
"{\n"
"\"string\":{\"type\":\"OurWideStringClass\",\"value\":\"bar\"},\r\n"
"\"int\":[\n"
"{\"type\":\"Int\"\"value\":7},\n"
"{\"type\":\"Int\",\"value\":11}\n"
"]\n"
"},\n"
"{\n"
"\"string\":{\"type\":\"OurWideStringClass\",\"value\":\"top\"},\n"
"\"int\":[\n"
"{\"type\":\"Int\",\"value\":13},\r\n"
"{\"type\":\"Int\",\"value\":41}\n"
"]\n"
"}\n"
"],\n"
"\"path2\":{\n"
"\"int\":{\"type\":\"Int\",\"value\":-1234},\n"
"\"double\":{\"type\":\"Double\",\"value\":-1.234}\r\n"
"}\n"
"}\n"
"}\n"; <=double clicking build error goes to this line
return j;
}
这是它的用法
OurWideStringClass slxStJson5 = BAD_JSON5_missingComma_multipleNewlines_Utf16MixedDosAndUnixLineEndings();
std::wistringstream ssJsonMissingCommaUtf16Newlines(slxStJson5);
我以为我的json中的wchar_t被std :: wstring覆盖了.有什么问题吗?您可以在\ u9ce5中看到我的utf16字符.这是此测试的关键.
I thought I had the wchar_t covered with std::wstring in my json. Any ideas what's the issue? you can see my utf16 character in \u9ce5. This is the key to this test.
我看着这个 c2440 ,但看不到它们在有关UDT的决议中指的是什么.
I looked at this c2440 but don't see what they are referring to in the resolution with regard to UDT.
I was looking at this which puts an L in front of it, but with escaped c string, I'm not sure where to put the L.
推荐答案
std::wstring
无法通过像"my string"
这样的窄字符串常量,因此编译错误.
std::wstring
cannot be initialized from a narrow string literal like "my string"
, hence the compilation error.
您可以通过宽字符串文字初始化std::wstring
—它的语法在开头的引号之前包含 L
前缀,例如L"my string"
.
You can initialize a std::wstring
from a wide string literal — its syntax includes the L
prefix before the opening quote, e.g. L"my string"
.
在使用字符串文字串联时,您需要在所有字符串文字前加上L
前缀,即:
As you are using string literal concatenation, you need to prefix all the string literals with L
, i.e.:
static std::wstring j =
L"{\n"
L"\"header\":{\n"
L"\"version\":{\"major\":1,\"minor\":0,\"build\":0}\n"
L"},\n"
...
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