Using The Remove Method with a Custom Object

[a]

If the code to insert a new Student is:
Profile.Teachers[tId].Classes[cId].Students.Add(new TCS.Student(id,teacher,
class, name));

what is the code to Remove a student?

I tried the code below, but I don't understand the syntax:
Profile.Teachers[tId].Classes[cId].Students.Remove(new TCS.Student(name));//
This line fails

Any ideas what I need to do to Remove a student based upon something other
than an index number(like their name)?

Thanks,

Paul

[Joanna Carter [TeamB]]

"a" <[e-mail]> a écrit dans le message de news:
E7**********************************@microsoft.com...

| If the code to insert a new Student is:
| Profile.Teachers[tId].Classes[cId].Students.Add(new
TCS.Student(id,teacher,
| class, name));
|
| what is the code to Remove a student?
|
| I tried the code below, but I don't understand the syntax:
| Profile.Teachers[tId].Classes[cId].Students.Remove(new
TCS.Student(name));//
| This line fails
|
| Any ideas what I need to do to Remove a student based upon something other
| than an index number(like their name)?

Just use the Student instance :

Profile.Teachers[tId].Classes[cId].Students.Add(new TCS.Student(id,teacher,
class, name));

TCS.Student student = Profile.Teachers[tId].Classes[cId].Students[id];

Profile.Teachers[tId].Classes[cId].Students.Remove(student);

Of course, you could redesign your collection classes to allow this
functionality.

Joanna

--
Joanna Carter [TeamB]
Consultant Software Engineer

[Ignacio Machin \( .NET/ C# MVP \)]

HI,

what is the code to Remove a student?

I tried the code below, but I don't understand the syntax:
Profile.Teachers[tId].Classes[cId].Students.Remove(new
TCS.Student(name));//
This line fails

you are creating a new studend and then deleting it from the collection, of
course as this new studend is not yet in the collection (and never will)
nothing happens

this is the correct code

TCS.Student toRemove = null;
foreach( TCS.Student item in Profile.Teachers[tId].Classes[cId].Students
if ( item.Name == name )
{
toRemove = item;
break;
}
if (toRemove!= null )
Profile.Teachers[tId].Classes[cId].Students.Remove( toRemove);

cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

[a]

Ignacio:

Thank you for your answer.

Paul
=======================================

"Ignacio Machin ( .NET/ C# MVP )" wrote:

HI,

what is the code to Remove a student?

I tried the code below, but I don't understand the syntax:
Profile.Teachers[tId].Classes[cId].Students.Remove(new
TCS.Student(name));//
This line fails

you are creating a new studend and then deleting it from the collection, of
course as this new studend is not yet in the collection (and never will)
nothing happens

this is the correct code

TCS.Student toRemove = null;
foreach( TCS.Student item in Profile.Teachers[tId].Classes[cId].Students
if ( item.Name == name )
{
toRemove = item;
break;
}
if (toRemove!= null )
Profile.Teachers[tId].Classes[cId].Students.Remove( toRemove);

cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

[a]

Joanna:

Thank you for giving me the answer.

This is my first custom object and as such I'm having trouble understanding
how to create it and how to use it.

You wrote: "Of course, you could redesign your collection classes to allow
this
functionality."

Can you recommend a book or other source to help me understand how to do
this, and if you have the time, How would you do this?

Thanks much for your help,
Paul
================================================

"Joanna Carter [TeamB]" wrote:

"a" <[e-mail]> a écrit dans le message de news:
E7**********************************@microsoft.com...

| If the code to insert a new Student is:
| Profile.Teachers[tId].Classes[cId].Students.Add(new
TCS.Student(id,teacher,
| class, name));
|
| what is the code to Remove a student?
|
| I tried the code below, but I don't understand the syntax:
| Profile.Teachers[tId].Classes[cId].Students.Remove(new
TCS.Student(name));//
| This line fails
|
| Any ideas what I need to do to Remove a student based upon something other
| than an index number(like their name)?

Just use the Student instance :

Profile.Teachers[tId].Classes[cId].Students.Add(new TCS.Student(id,teacher,
class, name));

TCS.Student student = Profile.Teachers[tId].Classes[cId].Students[id];

Profile.Teachers[tId].Classes[cId].Students.Remove(student);

Of course, you could redesign your collection classes to allow this
functionality.

Joanna

--
Joanna Carter [TeamB]
Consultant Software Engineer

[a]

Joanna:

This question is related to my first question.

I have a gridview that contains the student name, if I capture the student
name from the gridview like so:

string s = (GridView_Students.Rows[e.RowIndex].Cells[2].Text); // Student
Name

How can I find the student in my custom object collection by the student
name? Currently it appears that the only way to find the student is by an
index, like so:

TCS.Student student = Profile.Teachers[tId].Classes[cId].Students[id];

Thank you,
Paul

==================================================

"Joanna Carter [TeamB]" wrote:

"a" <[e-mail]> a écrit dans le message de news:
E7**********************************@microsoft.com...

| If the code to insert a new Student is:
| Profile.Teachers[tId].Classes[cId].Students.Add(new
TCS.Student(id,teacher,
| class, name));
|
| what is the code to Remove a student?
|
| I tried the code below, but I don't understand the syntax:
| Profile.Teachers[tId].Classes[cId].Students.Remove(new
TCS.Student(name));//
| This line fails
|
| Any ideas what I need to do to Remove a student based upon something other
| than an index number(like their name)?

Just use the Student instance :

Profile.Teachers[tId].Classes[cId].Students.Add(new TCS.Student(id,teacher,
class, name));

TCS.Student student = Profile.Teachers[tId].Classes[cId].Students[id];

Profile.Teachers[tId].Classes[cId].Students.Remove(student);

Of course, you could redesign your collection classes to allow this
functionality.

Joanna

--
Joanna Carter [TeamB]
Consultant Software Engineer

[a]

Joanna:

I just implemented the code that Ignacio Machin sent in answer to my first
question and using his code answers my second question to you about finding
the student by name instead of index number. At least it works if I need to
find all instances of the name...(not sure about finding a particular
instance of a name, though.)

Thanks,
Paul
================================

"Joanna Carter [TeamB]" wrote:

"a" <[e-mail]> a écrit dans le message de news:
E7**********************************@microsoft.com...

| If the code to insert a new Student is:
| Profile.Teachers[tId].Classes[cId].Students.Add(new
TCS.Student(id,teacher,
| class, name));
|
| what is the code to Remove a student?
|
| I tried the code below, but I don't understand the syntax:
| Profile.Teachers[tId].Classes[cId].Students.Remove(new
TCS.Student(name));//
| This line fails
|
| Any ideas what I need to do to Remove a student based upon something other
| than an index number(like their name)?

Just use the Student instance :

Profile.Teachers[tId].Classes[cId].Students.Add(new TCS.Student(id,teacher,
class, name));

TCS.Student student = Profile.Teachers[tId].Classes[cId].Students[id];

Profile.Teachers[tId].Classes[cId].Students.Remove(student);

Of course, you could redesign your collection classes to allow this
functionality.

Joanna

--
Joanna Carter [TeamB]
Consultant Software Engineer

[Marc Gravell]

Firstly - for the record I have developed solutions for managing
school/student records, and one thing we decided early: don't do *anything*
based on names (alone) [ok, except perhaps searching]. It's just too
unreliable - particularly when there are regional influences (religious,
political, historical, etc) on names. Up to you, though...

I know you've had several solutions; an additional few (in 2.0), depending
on what your Students class is:

if it involves List<Student> you could use the predicate syntax:

Students.RemoveAll(delegate(Student s) {return s.Name == name});

(of course, this won't "break" after the first one like Ignacio's
suggestion; maybe good, maybe bad)

Alternatively, if you can decide on a logical key (unique field) for your
objects, you could use (e.g. for the name) Dictionary<string, Student>,
whose Remove method will then take the string (of the name):

Students.Add(s.Name, s);
Students.Remove("Freddy");

Personally, I'd be looking for something more unique as my first port of
call... a database ID (primary key) is never a bad choice, although if there
is a logical existing figure (e.g. "UPN" = unique pupil number in some UK
circles) then this might be better.

Marc