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format string

If you have just SOlUTion
one value to format,
you don't need to
surround it with You were to match each format string to what it does.
parentheses.

"%s %e" % ("Value is", 16.0 ** 0.5) Display a string followed by 4.000000.

"%7d" % (11232/3) Display a string followed by 4.000000e+00.

"%x" % 127 Display the value, padded with 0s.
\n means take a NEWLINE.

"%20s\n" % "Banana swirl" Display the result of the calculation, padded
This means “use 4 characters." with spaces. By default, Python will pad
using spaces.
"%s is $%4.2f" % ("Popsicle", 1.754) Pad the string out to 20 characters, then display a
This means “show 2 numbers newline character.
after the decimal point."

"%s %f" % ("Value is", 16.0 ** 0.5) Display the number as a hexidecimal (base 16).
Values can be the
result of a calculation.
As well as a string, also display a floating point
"%07d" % (11232/3)
number to 2 decimal places. Hexadecimal numbers
Following the % with a 0 are used for things
means “pad with zeroes." like colors on the Web.

You were to look back at the records you need to create for the
transaction file and write down what you would use for the
Don't worry if your answer doesn't format string:
look EXACTLY like this. Try out your Multiplying by 100 and
answer in the Python Shell to check displaying it as a whole number
that it works. effectively removes the
decimal point from the price.
“%16s%07d%16s\n" % (credit_card, price*100, description)
Credit card numbers should always You need a newline character
be exactly 16 characters. at the end of each line.

182 Chapter 6