Output Formatting
- Michael Tomaino
- Nov 25, 2016
- 2 min read
For the haters in the audience - I'll get into the .format() method sometime in the future. I come from a school of thought that you need to evolve in your understanding as languages evolved - start procedural then get into object orientation and so forth.
This is the "old" way but it's easy to understand and learn - it has its roots in the C programming language's printf function. The term output formatting refers to making data look a certain way during output. For example, if the value of a variable pi is 3.1415926, but you didn't want that much space taken up on the screen, output formatting is your friend.
Try the following:
pi=3.1415926 # sets the value of the variable pi
print(pi) # prints 3.1415926 ... duh
print("%f" % pi) # creates a template string - the %f is the
# placeholder for a float
# then inserts the value of the variable pi
# interestingly outputs: 3.141593 (rounding?)
print("PI: %f" % pi) # shows how you can use
# placeholders anywhere in a string.
output="PI: %f" # assign the template string to a variable
print(output % pi) # shows the same output as above
# you can use a template in a string variable
print("PI: %.2f" % pi) # the %.2f says we want 2 places
# after the decimal: PI: 3.14 is output.
Look at the following interesting examples:
print("PI: %6.2f" % pi) # outputs - PI: 3.14
# notice the spaces before 3.14
# it's a 6 character field width
print("PI: %06.2f" % pi) # this time - PI: 003.14
# same 6 character field width
# but this time filled in with 0's
If you have more than one value to fill in, it needs to be in a tuple (comma separated list in parentheses)
print("Age: %i Height: %i'%i\"" % (16,5,10))
The general format is: %[flags][width][.precision]type
You can use templating or output formatting for the following types:





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