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A string and an integer to appear in tuple (python 2.7)

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  A string and an integer to appear in tuple (python 2.7) Jiewei Huang <jiewei24@gmail.com> - 2013-03-12 17:21 -0700
    Re: A string and an integer to appear in tuple (python 2.7) Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-03-13 00:43 +0000
    Re: A string and an integer to appear in tuple (python 2.7) Vlastimil Brom <vlastimil.brom@gmail.com> - 2013-03-13 02:06 +0100

#41156 — A string and an integer to appear in tuple (python 2.7)

Hi all,

I'm currently stuck at this question on 

Writing a function len_str that takes a string as an argument and returns a pair consisting of the length of the string and the string itself. 

Example: len_str('Meaning of life') should return the tuple (15, 'Meaning of life').


I can only think of this :

len_str = ('welcome to life' )

print (len(len_str,), len_str)


However that not an correct answer I need to make a def len_str but I can't seen to get it right.

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#41157

On 13 March 2013 00:21, Jiewei Huang <jiewei24@gmail.com> wrote:
> Hi all,
>
> I'm currently stuck at this question on
>
> Writing a function len_str that takes a string as an argument and returns a pair consisting of the length of the string and the string itself.
>
> Example: len_str('Meaning of life') should return the tuple (15, 'Meaning of life').
>
>
> I can only think of this :
>
> len_str = ('welcome to life' )
>
> print (len(len_str,), len_str)
>
>
> However that not an correct answer I need to make a def len_str but I can't seen to get it right.

Perhaps an example will help. Let's say we have a variable called x
that we initialise with

x = 2

Here's a line of code that prints 2*x:

print(2 * x)

This will print out 4 but that's not what you want. Here's a function
that prints its argument multiplied by 2:

def double(y):
    print(2 * y)

Now we have a function and we can call it with

double(x)

so that it prints 4. Again, though, you didn't want to print it. You
wanted to *return* the value. So here's a function that *returns* 2
times its argument:

def double(x):
    return 2 * x

Now if we do

z = double(x)

z will have the value 4. You can check this with

print(z)

Try the code above and see if you can apply the same principles to your problem.


Oscar

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#41158

2013/3/13 Jiewei Huang <jiewei24@gmail.com>:
> Hi all,
>
> I'm currently stuck at this question on
>
> Writing a function len_str that takes a string as an argument and returns a pair consisting of the length of the string and the string itself.
>
> Example: len_str('Meaning of life') should return the tuple (15, 'Meaning of life').
>
>
> I can only think of this :
>
> len_str = ('welcome to life' )
>
> print (len(len_str,), len_str)
>
>
> However that not an correct answer I need to make a def len_str but I can't seen to get it right.
> --
> http://mail.python.org/mailman/listinfo/python-list


Hi,
unless you are required to code the length-counting by hand as a part
of the exercise, you would simply use the built-in function for that,
i.e.
http://docs.python.org/3.3/library/functions.html#len

Tuples are created using the coma delimiter; optionally with enclosing parens.
http://docs.python.org/3.3/library/stdtypes.html#tuples

>>> input_string = "Meaning of life"
>>> input_string
'Meaning of life'
>>> len(input_string)
15
>>> (len(input_string), input_string)
(15, 'Meaning of life')
>>>

Now you have to put the needed code to the function body; see
http://docs.python.org/3.3/tutorial/controlflow.html#defining-functions

(Be sure not to forget the "return" statement containing the result of
your function.)

hth,
   vbr

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