Is using namespace std a bad practice?

The statement using namespace std is generally considered bad practice. The alternative to this statement is to specify the namespace to which the identifier belongs using the scope operator(::) each time we declare a type.

When should I use using namespace std?

So when we run a program to print something, “using namespace std” says if you find something that is not declared in the current scope go and check std. using namespace std; are used. It is because computer needs to know the code for the cout, cin functionalities and it needs to know which namespace they are defined.

What can I do instead of using namespace std?

The main alternatives to bringing in everything from the std namespace into the global one with using namespace std; at global scope are:

• Only bring in the actual names you need.
• Always use explicit namespace qualifications when you use a name.
• Bring in all names, but in a reduced scope (like only inside a function).

What will happen to your program if you forgot to put using namespace std?

When you don’t use the std namespace, the computer will try to call cout or cin as if it weren’t defined in a namespace (as most functions in your codes). Since it doesn’t exist there, the computer tries to call something that doesn’t exist! Hence, an error occurs.

What does namespace std mean?

the standard
It is known that “std” (abbreviation for the standard) is a namespace whose members are used in the program. So the members of the “std” namespace are cout, cin, endl, etc. This namespace is present in the iostream. h header file.

Where is std namespace defined?

An example of this is the std namespace which is declared in each of the header files in the standard library. Members of a named namespace can be defined outside the namespace in which they are declared by explicit qualification of the name being defined.