Cara menggunakan python get current exception

Question

In the last tutorial, we learned about Python exceptions. We know that exceptions abnormally terminate the execution of a program.

Table of Contents Show

Python try...except Block
Example: Exception Handling Using try...except
Catching Specific Exceptions in Python
Python try with else clause
Python try...finally

This is why it is important to handle exceptions. In Python, we use the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

0 block

Python try...except Block

The

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

0 block is used to handle exceptions in Python. Here's the syntax of

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

0 block:

try:
    # code that may cause exception
except:
    # code to run when exception occurs

Here, we have placed the code that might generate an exception inside the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block. Every

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block is followed by an

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 block.

When an exception occurs, it is caught by the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 block. The

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 block cannot be used without the try block.

Example: Exception Handling Using try...except

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

In the example, we are trying to divide a number by 0. Here, this code generates an exception.

To handle the exception, we have put the code,

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

8 inside the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block. Now when an exception occurs, the rest of the code inside the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block is skipped.

The

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 block catches the exception and statements inside the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 block are executed.

If none of the statements in the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block generates an exception, the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 block is skipped.

Catching Specific Exceptions in Python

For each

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block, there can be zero or more

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 blocks. Multiple

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 blocks allow us to handle each exception differently.

The argument type of each

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5 block indicates the type of exception that can be handled by it. For example,

try:
    
    even_numbers = [2,4,6,8]
    print(even_numbers[5])

except ZeroDivisionError:
    print("Denominator cannot be 0.")
    
except IndexError:
    print("Index Out of Bound.")

# Output: Index Out of Bound

In this example, we have created a list named even_numbers.

Since the list index starts from 0, the last element of the list is at index 3. Notice the statement,

print(even_numbers[5])

Here, we are trying to access a value to the index 5. Hence,

try:
    
    even_numbers = [2,4,6,8]
    print(even_numbers[5])

except ZeroDivisionError:
    print("Denominator cannot be 0.")
    
except IndexError:
    print("Index Out of Bound.")

# Output: Index Out of Bound

9 exception occurs.

When the

try:
    
    even_numbers = [2,4,6,8]
    print(even_numbers[5])

except ZeroDivisionError:
    print("Denominator cannot be 0.")
    
except IndexError:
    print("Index Out of Bound.")

# Output: Index Out of Bound

9 exception occurs in the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block,

The
```
print(even_numbers[5])
```
2 exception is skipped.

The set of code inside the

try:
    
    even_numbers = [2,4,6,8]
    print(even_numbers[5])

except ZeroDivisionError:
    print("Denominator cannot be 0.")
    
except IndexError:
    print("Index Out of Bound.")

# Output: Index Out of Bound

9 exception is executed.

Python try with else clause

In some situations, we might want to run a certain block of code if the code block inside

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 runs without any errors.

For these cases, you can use the optional

print(even_numbers[5])

5 keyword with the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 statement.

Let's look at an example:

# program to print the reciprocal of even numbers

try:
    num = int(input("Enter a number: "))
    assert num % 2 == 0
except:
    print("Not an even number!")
else:
    reciprocal = 1/num
    print(reciprocal)

Output

If we pass an odd number:

Enter a number: 1
Not an even number!

If we pass an even number, the reciprocal is computed and displayed.

Enter a number: 4
0.25

However, if we pass 0, we get

print(even_numbers[5])

2 as the code block inside

print(even_numbers[5])

5 is not handled by preceding

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

5.

Enter a number: 0
Traceback (most recent call last):
  File "", line 7, in 
    reciprocal = 1/num
ZeroDivisionError: division by zero

Note: Exceptions in the

print(even_numbers[5])

5 clause are not handled by the preceding except clauses.

Python try...finally

In Python, the

# program to print the reciprocal of even numbers

try:
    num = int(input("Enter a number: "))
    assert num % 2 == 0
except:
    print("Not an even number!")
else:
    reciprocal = 1/num
    print(reciprocal)

1 block is always executed no matter whether there is an exception or not.

The

# program to print the reciprocal of even numbers

try:
    num = int(input("Enter a number: "))
    assert num % 2 == 0
except:
    print("Not an even number!")
else:
    reciprocal = 1/num
    print(reciprocal)

1 block is optional. And, for each

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block, there can be only one

# program to print the reciprocal of even numbers

try:
    num = int(input("Enter a number: "))
    assert num % 2 == 0
except:
    print("Not an even number!")
else:
    reciprocal = 1/num
    print(reciprocal)

1 block.

Let's see an example,

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")
    
finally:
    print("This is finally block.")

Output

Error: Denominator cannot be 0.
This is finally block.

In the above example, we are dividing a number by 0 inside the

try:
    numerator = 10
    denominator = 0

    result = numerator/denominator

    print(result)
except:
    print("Error: Denominator cannot be 0.")

# Output: Error: Denominator cannot be 0.

3 block. Here, this code generates an exception.

kode python