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why is this variable not printing out properly? - Printable Version

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why is this variable not printing out properly? - dursland - Dec-27-2016

Using python3 and am new - learning via introtopython.org and I'm having a problem.

var1 = (2+2)

print('The result of all calculations is ' + var1 + ' and we are done.')
Which returns the error of
Quote:Traceback (most recent call last):
  File "test.py", line 3, in <module>
    print('The result of all calculations is ' + var1 + ' and we are done.')
TypeError: Can't convert 'int' object to str implicitly

What am I doing wrong? When I change the variable to a string the line executes properly.

RE: why is this variable not printing out properly? - Mekire - Dec-27-2016

(Dec-27-2016, 07:00 AM)dursland Wrote: When I change the variable to a string the line executes properly.
That is exactly it.  You can't concatenate a string and int.

The recommended way would be to use format.  String concatenation in general is not a great technique (though often the first thing taught >.>)

var1 = 2 + 2
 
print('The result of all calculations is {} and we are done.'.format(var1))


RE: why is this variable not printing out properly? - wavic - Dec-27-2016

Hello!
Using '+' for a string concatenation works but for strings. You are trying to concatenate a string with an integer without to convert the number into string - str(num).

@Mekire has showed you the proper way

RE: why is this variable not printing out properly? - dursland - Dec-27-2016

Thanks. Good to know, I'm following the lessons in order on introtopython.

RE: why is this variable not printing out properly? - snippsat - Dec-27-2016

Now that 3.6 is out,also f-string.
>>> var1 = 2 + 2
>>> print(f'The result of all calculations is {var1} and we are done.')
The result of all calculations is 4 and we are done.


RE: why is this variable not printing out properly? - Mekire - Dec-27-2016

(Dec-27-2016, 09:43 AM)snippsat Wrote: Now that 3.6 is out,also f-string.
Wow. That is a pretty neat addition.

RE: why is this variable not printing out properly? - sixteenornumber - Dec-27-2016

here is one more method.

>>> var1 = 2 + 2
>>> print "the result of all calculations is %s and we are done." % var1
the result of all calculations is 4 and we are done.
you can also print floats to a specific decimal place. 
>>> PI = 3.14159265389793
>>> print "Pi to the 2nd decimal place is %.02f" %PI
Pi to the 2nd decimal place is 3.14
>>> print "Pi to the 3rd decimal place is \"%.03f\" and pi to the 4th decimal place is \"%.04f\"." %(PI, PI)
Pi to the 3rd decimal place is "3.141" and pi to the 4th decimal place is "3.1415".


RE: why is this variable not printing out properly? - Mekire - Dec-27-2016

The % method of string formatting should really be considered deprecated (despite Zed's irrelevant opinion).
Everything that can be done with it can be done much more cleanly with format.

RE: why is this variable not printing out properly? - samRddhi - Dec-22-2017

Use 
print('The result of all calculations is ' + str(var1) + ' and we are done.')


RE: why is this variable not printing out properly? - IAMK - Apr-08-2018

(Dec-27-2016, 07:16 AM)Mekire Wrote: The recommended way would be to use format.  String concatenation in general is not a great technique (though often the first thing taught >.>)

var1 = 2 + 2
 
print('The result of all calculations is {} and we are done.'.format(var1))

Could you please explain why that is?
To me, a simple typecast to string seems cleaner.