Questions

Signature Writing

The following questions will have you practice signature writing.

1. What is a function signature, and why is it significant?

2. Write the function signature for a function called pos_or_neg that takes as input an integer and returns "Positive" if the integer is positive and returns "Negative" if the integer is negative. Use number as the name of the parameter.

3. Write the function signature for a function called gcd that takes two integers as input and returns the integer that is their greatest common divisor. Use num_one and num_two as your parameter names.

4. Write the signature for a function called name_eval that takes as input someone’s name as a string and returns True if the name has an even amount of letters and False if it has an odd amount of letters.

5. Write the signature for a function called name_size that takes as input someone’s name as a string and returns the length of their name as an integer.

6. Write the signature for a function called gcd that takes two floats as input and returns the integer that is their greatest common divisor.

solutions

Complete the function definition

1. Line 2 belongs within the body of a function. Add a line of code that will complete the entire function definition.

    
        return x * 2

    print(double(x=3))

2. Line 2 belongs within the body of a function. Add a line of code that will complete the entire function definition. The function’s name is my_string.

    
        return "This is my word, " + word

3. Line 2 belongs within the body of a function. Add a line of code to complete the entire function definition. The function’s name is my_num and word is a float.

    
        print("This is my number, " + str(word))

Solutions

Signature Writing Solutions

1. A function signature refers to the first line of a function definition, where the def keyword is used. Following the def keyword is the function name, and after the function name is a set of parentheses that enclose the parameter list. After the parameter list comes the return type. The function signature is important because it defines how the function can be called and what kinds of inputs and outputs are expected. Without a signature, you wouldn’t know what parameters to provide or even how to call the function, since the function name would be missing.

def pos_or_neg(number: int) -> str:

def gcd(num_one: int, num_two: int) -> int:

4. def name_eval(id: str) -> bool:

(Note that I chose to call the parameter id, but you could’ve chosen any valid name!)

5. def name_size(id: str) -> int:

(Note that I chose to call the parameter id, but you could’ve chosen any valid name!)

6. def gcd(number_a: float, number_b: float) -> int:

(Note that I chose to call the parameters number_a and number_b, but you could’ve chosen any valid name!)

Complete the function definition

1. Complete function definition

    def double(x: int) -> int:  # Added this line
        return x * 2

    print(double(x=3))

2. Complete function definition

    def my_string(word: str) -> str:  # Added this line
        return "This is my word, " + word

3. Complete function definition

    def my_num(word: float) -> None:  # Added this line
        print("This is my number, " + str(word))