Asp Forum - What is wrong in this code ... ???

Faisal Raja

7/5/2005 7:14:00 PM

Hello ,
Well Im new to programming in Ruby Language ( Infact only an hour back
i started it ) .

class Student

def initialize(name)

@name = name

end

def show

s = "Name : " + name
return s

end
end

st = Student.new("Abc") ;
st.inspect

I have Windows Xp Sp2 n when i run this program on console , it doesn't
show me anything . There is no error but it is also not shwoing me
anything .

st.inspect should show info
st.to_s also doesn't show anything

if i write st.show
it also doesn't work .
I wuld be thankful if u people help me out
Thanks in advance

9 Answers

threeve.org

7/5/2005 7:24:00 PM

On 7/5/05, Faisal Raja <Raja.Faisal@gmail.com> wrote:
> Hello ,
> Well Im new to programming in Ruby Language ( Infact only an hour back
> i started it ) .
>
> class Student
>
> def initialize(name)
>
> @name = name
>
> end
>
> def show
>
> s = "Name : " + name
> return s
>
>
> end
> end
>
>
> st = Student.new("Abc") ;
> st.inspect
>
> I have Windows Xp Sp2 n when i run this program on console , it doesn't
> show me anything . There is no error but it is also not shwoing me
> anything .
>

you aren't printing anything. Try putting "p st.inspect" instead of
just "st.inspect".

> st.inspect should show info
> st.to_s also doesn't show anything
>
>
> if i write st.show
> it also doesn't work .

this is because you reference 'name' which is a local variable, but
what you meant is to access '@name' which is the instance variable.

Try this instead: s = "Name: " + @name

> I wuld be thankful if u people help me out
> Thanks in advance
>
>
>

Jason

Jared Richardson

7/5/2005 7:30:00 PM

I'm no Ruby guru (and I'm sure you'll hear from others soon), but if you add

def printName
puts @name
end

then use this

st = Student.new("Abc") ;
#st.inspect
st.printName

you can run it like so:

C:\dev\ruby>student.rb testName
Abc

C:\dev\ruby>

Jared

Ship It! is shipping!
http://www.jaredrich...
http://www.pragmaticprogrammer.com/t...

"Faisal Raja" <Raja.Faisal@gmail.com> wrote in message
news:1120590863.719406.196200@o13g2000cwo.googlegroups.com...
> Hello ,
> Well Im new to programming in Ruby Language ( Infact only an hour back
> i started it ) .
>
> class Student
>
> def initialize(name)
>
> @name = name
>
> end
>
> def show
>
> s = "Name : " + name
> return s
>
>
> end
> end
>
>
> st = Student.new("Abc") ;
> st.inspect
>
> I have Windows Xp Sp2 n when i run this program on console , it doesn't
> show me anything . There is no error but it is also not shwoing me
> anything .
>
> st.inspect should show info
> st.to_s also doesn't show anything
>
>
> if i write st.show
> it also doesn't work .
> I wuld be thankful if u people help me out
> Thanks in advance
>

Daniel Nugent

7/5/2005 7:37:00 PM

The extra assignment is unnecessary too.

you can just do

def show
return "Name: " + @name
end

With instance and class variables, the @'s are part of the name themselves.

This is a nice thing because you can always tell whether you're
looking at a class variable, a local variable, or an instance
variable.

On 7/5/05, Jason Foreman <threeve.org@gmail.com> wrote:
> On 7/5/05, Faisal Raja <Raja.Faisal@gmail.com> wrote:
> > Hello ,
> > Well Im new to programming in Ruby Language ( Infact only an hour back
> > i started it ) .
> >
> > class Student
> >
> > def initialize(name)
> >
> > @name = name
> >
> > end
> >
> > def show
> >
> > s = "Name : " + name
> > return s
> >
> >
> > end
> > end
> >
> >
> > st = Student.new("Abc") ;
> > st.inspect
> >
> > I have Windows Xp Sp2 n when i run this program on console , it doesn't
> > show me anything . There is no error but it is also not shwoing me
> > anything .
> >
>
> you aren't printing anything. Try putting "p st.inspect" instead of
> just "st.inspect".
>
> > st.inspect should show info
> > st.to_s also doesn't show anything
> >
> >
> > if i write st.show
> > it also doesn't work .
>
> this is because you reference 'name' which is a local variable, but
> what you meant is to access '@name' which is the instance variable.
>
> Try this instead: s = "Name: " + @name
>
> > I wuld be thankful if u people help me out
> > Thanks in advance
> >
> >
> >
>
>
> Jason
>
>

--
-Dan Nugent

Gavin Kistner

7/5/2005 7:44:00 PM

On Jul 5, 2005, at 1:37 PM, Daniel Nugent wrote:
> The extra assignment is unnecessary too.
>
> you can just do
>
> def show
> return "Name: " + @name
> end

Or, because the last value in a method is the return value (in the
absence of a call to the #return method) you can simply do:

def show
"Name: " + @name
end

or, even better, use string interpolation:

def show
"Name: #{@name}"
end

and finally, because instance variables are special, even:

def show
"Name: #@name"
end

will work.

Faisal Raja

7/5/2005 7:48:00 PM

Well , p st.inspect worked ... thanks .
What this 'p' represent ??? .... why we need to include it .

Belorion

7/5/2005 7:53:00 PM

On 7/5/05, Faisal Raja <Raja.Faisal@gmail.com> wrote:
> Well , p st.inspect worked ... thanks .
> What this 'p' represent ??? .... why we need to include it .

st.inspect just returns "... a string containing a human-readable
representation of obj"

You can do whatever you want with that string -- it does not assume
you want to send it to STDOUT.

p st.inspect is short for print st.inspect, which sends the string to STDOUT.

Matt

Faisal Raja

7/5/2005 7:57:00 PM

Well I got it . Thanks you every1 , for helping
U people have given me some useful things .

May U all be blessed

Faisal Raja

7/5/2005 7:57:00 PM

Well I got it . Thanks you every1 , for helping
U people have given me some useful things .

May U all be blessed

mathew

7/8/2005 5:46:00 PM

Well, if we're doing stylistic suggestions... :-)

class Student
attr_accessor :name

def initialize(name)
@name = name
end

def to_s
return "Name: #{@name}"
end
end

attr_accessor is an easy way to set up a read/write instance variable;
it creates an accessor method so you can go object.name = "John Smith"
or puts object.name

There's also attr_reader to set up a read-only field, and attr_writer
for write-only.

The to_s method is the standard method used to convert an object to a
string; so if you define it to be something sensible, you can just print
or puts the object directly.

So, we can now do

s = Student.new("John Smith")
puts s
s.name = "John P. Smith"
puts s.name

mathew

comp.lang.ruby

What is wrong in this code ... ???

Faisal Raja

threeve.org

Jared Richardson

Daniel Nugent

Gavin Kistner

Faisal Raja

Belorion

Faisal Raja

Faisal Raja

mathew

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