programming-for-dummies

220
Passing Parameters
This BASIC language example defines a subprogram named PrintMyName,
which accepts two parameters. The first parameter is an integer variable —
PrintTimes — which defines how many times to print a name.
The second parameter is a string variable — Name — which defines the
name to print multiple times.
Every programming language offers slightly different ways of creating a subprogram.
Here’s what an equivalent Python subprogram might look like:
def print_my_name(printtimes, name):
for i in range(printtimes):
print name
By writing a generic subprogram that accepts parameters, you can create a
single subprogram that can behave differently, depending on the parameters
it receives.
To give or pass parameters to a subprogram, you need to call the subprogram
by name along with the parameters you want to give that subprogram.
So if a subprogram accepted two parameters (an integer and a string), you
could call that subprogram by doing the following:
PrintMyName (5, “John Smith”)
PrintMyName (16, “Mary Jones”)
The first command tells the PrintMyName subprogram to use the number 5
and the string John Smith as its parameters. Because the number defines
how many times to print and the string defines what to print, this first command
tells the PrintMyName subprogram to print John Smith five times.
The second command tells the PrintMyName subprogram to use the
number 16 and the string Mary Jones as its parameters, which prints Mary
Jones 16 times, as shown in Figure 6-5.
Calling a subprogram works the same way in other programming languages.
So if you want to call the following Python subprogram:
def print_my_name(printtimes, name):
for i in range(printtimes):
print name
You could print the name John Smith four times with this command:
print_my_name(4, “John Smith”)