Concatenate string and int in python 3.4

Question

I\'m new to Python, so I\'ve been running through my own set of exercises to simply start memorizing basic functions and syntax. I\'m using Pycharm IDE and Python 3.4. I\'ve

Answer 1

What's wrong with this?

print ("Type string: ") + str(123)

print is just a function like anything else. And you're calling that function with one argument, "Type string: ", and then trying to add the result (which will be None) to the string '123'. That isn't going to work. If you wanted to add the two strings together, you have to put them into the same expression, inside the parens:

print("Type string: " + str(123))

Similarly:

print ("Concatenate strings and ints "), 10

This calls print with one argument, and then makes a tuple of the None returned by print and the number 10. If you want to pass 10 to the print call, it has to go inside the parens:

print("Concatenate strings and ints ", 10)

As rednaw's answer points out, using str.format is more flexible, and avoids the possibility of problems like this. It also gives you code that works exactly the same way in both Python 2.6-2.7 and Python 3.x, which is pretty nice even if you aren't trying to write dual-platform/single-codebase code, because it'll be understandable even to people who only know one or the other.