C++ 'cout' 未在此范围内声明
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'cout' was not declared in this scope
提问by rafalon
I have a C++ program:
我有一个 C++ 程序：
test.cpp
测试.cpp
#include<iostream>
int main()
{
char t = 'f';
char *t1;
char **t2;
cout<<t; //this causes an error, cout was not declared in this scope
return 0;
}
I get the error:
我收到错误：
'cout' was not declared in this scope
'cout' 未在此范围内声明
Why?
为什么？
回答by rafalon
Put the following code before int main():
将以下代码放在前面int main()：
using namespace std;
And you will be able to use cout.
您将能够使用cout.
For example:
例如：
#include<iostream>
using namespace std;
int main(){
char t = 'f';
char *t1;
char **t2;
cout<<t;
return 0;
}
Now take a moment and read up on what cout is and what is going on here: http://www.cplusplus.com/reference/iostream/cout/
现在花点时间阅读一下 cout 是什么以及这里发生了什么：http: //www.cplusplus.com/reference/iostream/cout/
Further, while its quick to do and it works, this is not exactly a good advice to simply add using namespace std;at the top of your code. For detailed correct approach, please read the answers to this related SO question.
此外，虽然它可以快速完成并且可以工作，但这并不是简单地using namespace std;在代码顶部添加的好建议。有关详细的正确方法，请阅读此相关 SO 问题的答案。
回答by Andy Prowl
Use std::cout, since coutis defined within the stdnamespace. Alternatively, add a using std::cout;directive.
使用std::cout, 因为cout是在std命名空间中定义的。或者，添加using std::cout;指令。
