我的char数组使用VisualStudio2017 C++切断了318个字符

Question

你好，我有一个问题，我的char arrays (strings)不能显示任何过去的318 characters。如果我做了一个std::string，它会很好，并显示整个事情.但是，如果我试图使用std::string.c_str()将其转换为char数组，它只会再次生成第一个318 characters。任何帮助都将不胜感激。我在用Visual Studio 2017。实际的字符串长度是517chars。

例如..。

std::string x = "INSERT INTO oms.Customers (customerFirstName, CustomerMiddleInitial, customerLastName, customerPrefixSuffix, customerCompanyName, customerStreetReference, customerStreetAddress, customerCity, customerState, customerZip, CountryID, customerPhoneNumber, customerEmail, customerIsCompany, customerIsActive) Values('Bill', '
INSERT INTO oms.Customers(customerFirstName, CustomerMiddleInitial, customerLastName, customerPrefixSuffix, customerCompanyName, customerStreetReference, customerStreetAddress, customerCity, customerState, customerZip, CountryID, customerPhoneNumber, customerEmail, customerIsCompany, customerIsActive)Values('Bill', ' ', 'Cosby', '', 'The Cosby Show', 'Studio A', '1818 broadway st', 'Philadelphia', 'PA', '19809', '', '6169875942', 'Bill.Cosby@ididntdoit.com', '', ');SELECT SCOPE_IDENTITY() AS [SCOPE_IDENTITY];"

但是如果我做了任何类型的char数组，就像我做了

char *y;
y= x.c_str

只有下面的内容才会显示

INSERT INTO oms.Customers (customerFirstName, CustomerMiddleInitial, customerLastName, customerPrefixSuffix, customerCompanyName, customerStreetReference, customerStreetAddress, customerCity, customerState, customerZip, CountryID, customerPhoneNumber, customerEmail, customerIsCompany, customerIsActive) Values('Bill', '

如果我做了strlen(y)，我就会得到318。如果我做了x.length()，我就会得到517。

任何帮助都将不胜感激。谢谢。

Answer 1

std::string可能包含'\0'字符，这些字符将被strlen(y)标识为C样式NUL终止字符串结束标记。

这就是为什么strlen()和std::string::length()的结果不同的原因。

Answer 2

如果我把绳子弄成原样：

std::string x = R"(INSERT INTO oms.Customers (customerFirstName, CustomerMiddleInitial, customerLastName, customerPrefixSuffix, customerCompanyName, customerStreetReference,
        customerStreetAddress, customerCity, customerState, customerZip, CountryID, customerPhoneNumber, customerEmail, customerIsCompany, customerIsActive) Values('Bill',
        '

            INSERT INTO oms.Customers(customerFirstName, CustomerMiddleInitial, customerLastName, customerPrefixSuffix, customerCompanyName, customerStreetReference,
                customerStreetAddress, customerCity, customerState, customerZip, CountryID, customerPhoneNumber, customerEmail, customerIsCompany, customerIsActive)Values('Bill',
                    ' ', 'Cosby', '', 'The Cosby Show', 'Studio A', '1818 broadway st', 'Philadelphia', 'PA', '19809', '', '6169875942', 'Bill.Cosby@ididntdoit.com', '', ');SELECT
                    SCOPE_IDENTITY() AS[SCOPE_IDENTITY]; )";
                    char const *pStr = x.c_str();
                    _RPTA("strlen: %d\r\n", strlen(pStr));

长度打印为857 (_RPTA是一个自定义宏，它输出到VS调试跟踪，而不是像printf那样的程序控制台)。