Question

I have an array of structures:

Public Structure emp
    Public empName As String
    Public empAge As Int32
    Public empsal As Int32 ' salary
End Structure

An array of the above structure with 30 element. I want to sum the empsal of those emp elements whose emp.empName & emp.empAge is equal.

for ex.

emp(0).empName = "test"
emp(0).empAge = 32
emp(0).empsal = 10000

emp(1).empName = "test"
emp(1).empAge = 32
emp(1).empsal = 10000

emp(2).empName = "test12"
emp(2).empAge = 32
emp(2).empsal = 10000

How can this be done so that the result will be (test,20000) and (test12,10000)?

Using .NET 3.5

Answer 1

EDIT: Edited the samples to include the age in the key, and to end up with an emp array.

Absolutely. You should look at LINQ for this – you basically want to group by name and age, and then sum the salary. In C# you’d write something like:

var query = employees.GroupBy
     (x => new { x.empName, x.empAge },
      x => x.empSal,
      (key, salaries) => new emp { empName = key.empName,
                                   empAge = key.empAge,
                                   empSalary = salaries.Sum() })
var array = query.ToArray();

I think in VB this would be something like:

Dim query = employees.GroupBy( _
    Function(x) New With { Key .Name = x.empName, Key .Age = x.empAge }, _
    Function(x) x.empSal, _
    Function(k, salaries) New Emp With _
         { .empName = k.Name, .empAge = k.Age, .empSalary = salaries.Sum() }_
    )
Dim array = query.ToArray()

See the GroupBy documentation for more details.

As an aside, I would recommend:

• Giving your type a fuller name which follows .NET naming conventions
• Making it a class rather than a structure (it’s not really a single value, like an int)
• Using properties instead of public fields
• Removing the emp prefix from the fields/properties – they’re already part of an employee type, after all