Try–except–else behavior in Python - Step-by-Step Execution

Concept Flow - Try–except–else behavior

Start try block

↓

Code runs without error?

No→Go to except block

↓

Handle exception

↓

Run else block

↓

Continue after try-except-else

The program tries code in try block; if no error, else runs; if error, except runs.

Execution Sample

Python

try:
    x = 10 / 2
except ZeroDivisionError:
    print("Error")
else:
    print("No error, result is", x)

This code divides 10 by 2, no error occurs, so else block prints the result.

Execution Table

Step	Action	Evaluation	Result
1	Enter try block	x = 10 / 2	x = 5.0
2	Check for error	No error	Proceed to else
3	Run else block	print("No error, result is", x)	Output: No error, result is 5.0
4	Exit try-except-else	End of blocks	Program continues normally

💡 No exception raised, so except block skipped; else block executed.

Variable Tracker

Variable	Start	After Step 1	After Step 4
x	undefined	5.0	5.0

Key Moments - 2 Insights

Why does the else block run only if no exception occurs?

Because the else block is designed to run only when the try block finishes without errors, as shown in execution_table step 2 and 3.

What happens if an exception occurs in the try block?

The program jumps to the except block to handle the error and skips the else block, which is shown by the flow in concept_flow.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of x after step 1?

A 10

B undefined

C 5.0

D ZeroDivisionError

💡 Hint

Check the 'Result' column in row for step 1 in execution_table.

At which step does the else block run?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Action' column in execution_table where else block is executed.

If a ZeroDivisionError occurred, which block would run instead of else?

A except block

B else block

C try block

D finally block

💡 Hint

Refer to concept_flow where error leads to except block.

Concept Snapshot

try:
  # code that might fail
except ErrorType:
  # handle error
else:
  # runs only if no error

Use else to run code only when try succeeds.

Full Transcript

This visual shows how Python's try-except-else works. First, the program runs code inside try. If no error happens, it runs the else block next. If an error occurs, it skips else and runs except block to handle it. Variables like x change only if try code runs without error. This helps keep error handling clear and separate from normal code.