未定义模板'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'的隐式

Question

在我一直在做的项目中，我们必须将 Cocoa 通知从C++子项目发送到它上面的主项目。为此，我们构造一个映射来充当通知的 userInfo 字典的键值存储。

在其中一个项目中，以下代码可以很好地编译：

std::map<std::string, std::string> *userInfo = new std::map<std::string, std::string>;
char buffer[255];
sprintf(buffer, "%i", intValue1);
userInfo->insert(std::pair<std::string, std::string>("intValue1", std::string(buffer)));
sprintf(buffer, "%i", intValue2);
userInfo->insert(std::pair<std::string, std::string>("intValue2", std::string(buffer)));
if(condition)
    userInfo->insert(std::pair<std::string, std::string>("conditionalValue", "true"));
PostCocoaNotification("notificationName", *userInfo);

但是，当将其复制到另一个子项目中的相同文件中时，编译器会在 userInfo->insert 调用上引发以下内容：

"Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'" 

..并且它找不到 PostCocoaNotification 的函数：

No matching function for call to 'PostCocoaNotification'

此外，它还会在系统标头中引发以下错误：

/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:73:11: Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:74:11: Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:73:11: Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_tree.h:1324:13: Cannot initialize a parameter of type '_Link_type' (aka '_Rb_tree_node<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > *') with an rvalue of type '_Const_Link_type' (aka 'const _Rb_tree_node<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > *')

我不知道我做了什么来造成这种混乱，尤其是当代码在另一个子项目中运行良好（成功发送通知）时。非常欢迎对这个问题有任何见解。

Answer 1

您需要包含以下标头：

#include <string>

Answer 2

我在尝试使用std::stringstream类时遇到了同样的错误。 添加此头文件：

#include <sstream>