C#•10mo ago

✅ using keyword as a directive

Hello guys, I'm a bit confused of how the

using

using

keyword is used with a namespace. Say I created a new project. At the root of that project we have a solution and inside that solution we have our project folder. Now, the namespace refers to the individual project folder we have?

Consider the picture for example. The namespace is the same for every .cs file in a particular project? Why can't we do

using LibraryManagement.BankAccount

using LibraryManagement.BankAccount

using LibraryManagement.BankAccount

using LibraryManagement.BankAccount? What I'm trying to say is, look inside the LibraryManagementFolder and import the BankAccount class but this is incorrect to interpret it like that?

Second thing, consider the following code:

C#
namespace LibraryManagement;

public class BankAccount
{
    public string Number { get; }
    public string Owner { get; set; }
    public decimal Balance { get; }
    
    public BankAccount(string name, decimal initialBalance)
    {
        Owner = name;
        Balance = initialBalance;
    }

    public void MakeDeposit(decimal amount, DateTime date, string note)
    {
        
    }

    public void MakeWithdrawal(decimal amount, DateTime date, string note)
    {
        
    }
}

C#
namespace LibraryManagement;

public class BankAccount
{
    public string Number { get; }
    public string Owner { get; set; }
    public decimal Balance { get; }
    
    public BankAccount(string name, decimal initialBalance)
    {
        Owner = name;
        Balance = initialBalance;
    }

    public void MakeDeposit(decimal amount, DateTime date, string note)
    {
        
    }

    public void MakeWithdrawal(decimal amount, DateTime date, string note)
    {
        
    }
}

C#
namespace LibraryManagement;

public class BankAccount
{
    public string Number { get; }
    public string Owner { get; set; }
    public decimal Balance { get; }
    
    public BankAccount(string name, decimal initialBalance)
    {
        Owner = name;
        Balance = initialBalance;
    }

    public void MakeDeposit(decimal amount, DateTime date, string note)
    {
        
    }

    public void MakeWithdrawal(decimal amount, DateTime date, string note)
    {
        
    }
}

C#
namespace LibraryManagement;

public class BankAccount
{
    public string Number { get; }
    public string Owner { get; set; }
    public decimal Balance { get; }
    
    public BankAccount(string name, decimal initialBalance)
    {
        Owner = name;
        Balance = initialBalance;
    }

    public void MakeDeposit(decimal amount, DateTime date, string note)
    {
        
    }

    public void MakeWithdrawal(decimal amount, DateTime date, string note)
    {
        
    }
}

When we don't use top-level statement, the namespace should explicitly been set? What the difference between a

namespace

namespace

namespace

namespace and the

using

using

keyword directive here please

Pobiega•2/26/25, 8:07 AM

BankAccountBankAccount isn't a namespace, its a class.

Pobiega•2/26/25, 8:08 AM

using

using

for namespaces just "imports" that namespace so you can access it without fully qualifing

Pobiega•2/26/25, 8:10 AM

ie, without using LibraryManagementusing LibraryManagement you could still use BankAccountBankAccount, but you'd have to write LibraryManagement.BankAccount account = new LibraryManagement.BankAccount();LibraryManagement.BankAccount account = new LibraryManagement.BankAccount(); etc

Pobiega•2/26/25, 8:11 AM

files and directories have no direct connection to namespaces, its just convention to align them most of the time, but there are valid exceptions

PPobiega ie, without `using LibraryManagement` you could still use `BankAccount`, but you...

FakerOP•2/26/25, 8:12 AM

one thing I don't understand, why even though BankAccount is in the same namespace, we need to use the line using LibraryManagementusing LibraryManagement

FakerOP•2/26/25, 8:12 AM

Like our IDE doesn't already know we are in the LibraryManagement project/namespace?

Pobiega•2/26/25, 8:12 AM

TLS files don't have a namespace

Pobiega•2/26/25, 8:13 AM

they are namespace-less

FakerOP•2/26/25, 8:13 AM

ahh

FakerOP•2/26/25, 8:13 AM

I thought behind the scenes we were already saying "using ...."

Pobiega•2/26/25, 8:13 AM

nope.

FakerOP•2/26/25, 8:13 AM

yeep I see, it's clearer now, thanks !

✅ using keyword as a directive

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