什么要求我声明“using namespace std;”? [英] What requires me to declare "using namespace std;"?
问题描述
这个问题可能是重复的,但我找不到一个好的答案。简单,需要我声明
This question may be a duplicate, but I can't find a good answer. Short and simple, what requires me to declare
using namespace std;
在C ++程序中?
推荐答案
由于C ++标准已被接受,几乎所有的标准库都在std命名空间内。因此,如果您不想使用 std ::
限定所有标准库调用,则需要添加using指令。
Since the C++ standard has been accepted, practically all of the standard library is inside the std namespace. So if you don't want to qualify all standard library calls with std::
, you need to add the using directive.
但是,
using namespace std;
被认为是一种坏习惯,因为实际上是导入整个标准命名空间,因此打开了很多名称冲突的可能性。最好只导入你实际在代码中使用的东西,例如
is considered a bad practice because you are practically importing the whole standard namespace, thus opening up a lot of possibilities for name clashes. It is better to import only the stuff you are actually using in your code, like
using std::string;
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