C++ 为什么我不能在我的程序中声明一个字符串：“字符串是未声明的标识符”
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Why can't I declare a string in my program: "string is undeclared identifier"
提问by Trent
I can't declare a string in my program:
我不能在我的程序中声明一个字符串：
string MessageBoxText = CharNameTextBox->Text;
it just doesn't work. It says string is undeclared identifier. What am I missing in the namespace or include or something like that?
它只是不起作用。它说string is undeclared identifier。我在命名空间或包含或类似的东西中缺少什么？
回答by
Make sure you've included this header:
确保您已包含此标题：
#include <string>
And then use std::stringinstead of string. It is because stringis defined in stdnamespace.
然后使用std::string代替string。这是因为string在std命名空间中定义。
And don't write this at namespace scope:
并且不要在命名空间范围内写这个：
using namespace std; //bad practice if you write this at namespace scope
However, writing it at function scope is not that bad. But the best is one which I suggested before:
但是，在函数范围内编写它并没有那么糟糕。但最好的是我之前建议的：
Use std::stringas:
使用std::string如：
std::string MessageBoxText = CharNameTextBox->Text;
回答by CB Bailey
To use the standard stringclass in C++ you need to #include <string>. Once you've added the #includedirective stringwill be defined in the stdnamespace and you can refer to it as std::string.
要string在 C++ 中使用标准类，您需要#include <string>. 添加#include指令后，string将在std命名空间中定义该指令，您可以将其称为std::string.
E.g.
例如
#include <string>
#include <iostream>
int main()
{
std::string hw( "Hello, world!\n" );
std::cout << hw;
return 0;
}
回答by dalle
Are you by any way compiling using C++/CLI, the Microsoft extension for .NET, and not standard ISO C++?
您是否以任何方式使用 C++/CLI、Microsoft .NET 扩展而不是标准 ISO C++ 进行编译？
In that case you should do the following:
在这种情况下，您应该执行以下操作：
System::String^ MessageBoxText = CharNameTextBox->Text;
Also see the following articles:
另请参阅以下文章：
