5.9. Parameters and arguments¶
Some of the built-in functions we have seen require arguments. For
example, when you call math.sin, you pass a number as an
argument. Some functions take more than one argument:
math.pow takes two, the base and the exponent.
Inside the function, the arguments are assigned to variables called parameters. Here is an example of a user-defined function that takes an argument:
def print_twice(bruce):
print(bruce)
print(bruce)
This function assigns the argument to a parameter named
bruce. When the function is called, it prints the value of
the parameter (whatever it is) twice.
This function works with any value that can be printed.
Activity: CodeLens 5.9.2 (functParam_codelens1)
The same rules of composition that apply to built-in functions also
apply to user-defined functions, so we can use any kind of expression as
an argument for print_twice:
Activity: CodeLens 5.9.3 (functParam_codelens2)
The argument is evaluated before the function is called, so in the
examples the expressions 'Spam '*4 and math.cos(math.pi)
are only evaluated once.
You can also use a variable as an argument:
Activity: CodeLens 5.9.4 (functParam_codelens3)
The name of the variable we pass as an argument (michael)
has nothing to do with the name of the parameter (bruce).
It doesn’t matter what the value was called back home (in the caller);
here in print_twice, we call everybody bruce.
- 67 (on the same line)
- Incorrect! In Python, each print statement automatically adds a new line after printing whatever is inside the print statement. Try again.
- 67 (on two separate lines)
- Correct! Even though the variable "hi" was changed in the functions, its value outside the functions remains the same, and print statements automatically add a new line.
- 69 (on two separate lines)
- Incorrect! Even though the variable "hi" was changed in the functions, its value outside the functions remains the same unless specified. Try again.
- 69 (on the same line)
- Incorrect! In Python, each print statement automatically adds a new line after printing whatever is inside the print statement. Try again.
Q-5: Consider the code block below. What prints?
def add_two(num):
num = num + 2
print(num)
def add_three(nums):
nums = nums + 3
print(nums)
hi = 4
add_two(hi)
add_three(hi)
Construct a block of code with four functions, defined in this order: printName, printGPA, printAttendance, printStudentInfo. printStudentInfo should call the other three functions which will print all of the student’s information. Be mindful of indentation!