Python Language Print basics


In Python 3 and higher, print is a function rather than a keyword.

print('hello world!')
# out: hello world!

foo = 1
bar = 'bar'
baz = 3.14

# out: 1
# out: bar
# out: 3.14

You can also pass a number of parameters to print:

print(foo, bar, baz)
# out: 1 bar 3.14

Another way to print multiple parameters is by using a +

print(str(foo) + " " + bar + " " + str(baz))
# out: 1 bar 3.14

What you should be careful about when using + to print multiple parameters, though, is that the type of the parameters should be the same. Trying to print the above example without the cast to string first would result in an error, because it would try to add the number 1 to the string "bar" and add that to the number 3.14.

# Wrong:
# type:int  str  float
print(foo + bar + baz)
# will result in an error

This is because the content of print will be evaluated first:

print(4 + 5)
# out: 9
print("4" + "5")
# out: 45
print([4] + [5])
# out: [4, 5]

Otherwise, using a + can be very helpful for a user to read output of variables In the example below the output is very easy to read!

The script below demonstrates this

import random 
#telling python to include a function to create random numbers
randnum = random.randint(0, 12) 
#make a random number between 0 and 12 and assign it to a variable
print("The randomly generated number was - " + str(randnum))

You can prevent the print function from automatically printing a newline by using the end parameter:

print("this has no newline at the end of it... ", end="")
# out: this has no newline at the end of it... see?

If you want to write to a file, you can pass it as the parameter file:

with open('my_file.txt', 'w+') as my_file:
    print("this goes to the file!", file=my_file)

this goes to the file!