Methods with return values in Python - Step-by-Step Execution

Concept Flow - Methods with return values

Define method

↓

Call method

↓

Execute method body

↓

Return value

↓

Receive returned value

↓

Use returned value

This flow shows how a method is defined, called, executes, returns a value, and how that value is used.

Execution Sample

Python

def add(a, b):
    return a + b

result = add(3, 4)
print(result)

This code defines a method that adds two numbers and returns the sum, then prints the result.

Execution Table

Step	Action	Evaluation	Result
1	Define method 'add'	Store function with parameters a, b	Method ready to call
2	Call add(3, 4)	Parameters a=3, b=4	Enter method body
3	Calculate a + b	3 + 4	7
4	Return 7	Return value sent back	Method call replaced by 7
5	Assign result = 7	Store 7 in variable 'result'	result = 7
6	Print result	Output value of result	7
7	End	No more code	Program stops

💡 Program ends after printing the returned value 7

Variable Tracker

Variable	Start	After Step 4	After Step 5	Final
a	N/A	3	3	3
b	N/A	4	4	4
result	Undefined	Undefined	7	7

Key Moments - 2 Insights

Why do we need the 'return' statement inside the method?

The 'return' sends the result back to where the method was called, as shown in step 4 of the execution_table. Without it, the method would not give any output to use.

What happens to the method call after it returns a value?

After returning, the method call is replaced by the returned value (step 4). This value can then be assigned or used elsewhere, like in step 5 where 'result' gets the value 7.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'result' after step 5?

A 3

B Undefined

C 7

D 4

💡 Hint

Check the 'result' variable in variable_tracker after step 5

At which step does the method return its value?

A Step 4

B Step 2

C Step 5

D Step 6

💡 Hint

Look at the 'Return 7' action in the execution_table

If the method did not have a return statement, what would 'result' be after step 5?

A 7

B None

C Error

D 3

💡 Hint

In Python, a method without return returns None by default

Concept Snapshot

def method_name(params):
    return value

- 'return' sends value back to caller
- Caller can store or use returned value
- Without return, method returns None
- Use returned value to continue program logic

Full Transcript

This lesson shows how methods with return values work in Python. First, a method is defined with parameters. When called, the method runs its code and uses 'return' to send a value back. The returned value replaces the method call and can be stored in a variable or used directly. For example, a method adding two numbers returns their sum, which can then be printed or used elsewhere. The 'return' statement is essential to get output from a method. Without it, the method returns None by default. This flow helps organize code and reuse logic with results.