except — Intermediate Examples

Catches and handles exceptions raised in a try block

EasyIntermediateAdvancedExpert

Multiple exceptions and hierarchy

Catching exception groups and using inheritance.

python
# Catch multiple types in one except
try:
    d = {}
    print(d["key"])
except (KeyError, IndexError) as e:
    print(f"Lookup failed: {type(e).__name__}: {e}")

# Exception hierarchy
try:
    int("abc")
except Exception as e:
    print(f"Caught via base class: {type(e).__name__}: {e}")

# Order matters: specific before general
def safe_convert(value):
    try:
        return int(value)
    except ValueError:
        print(f"  ValueError for {value!r}")
        return None
    except TypeError:
        print(f"  TypeError for {value!r}")
        return None
    except Exception as e:
        print(f"  Unexpected: {e}")
        return None

for v in ["42", "abc", None, 3.14]:
    print(f"{v!r} -> {safe_convert(v)}")

Catch specific exceptions first, then broader ones. All exceptions inherit from BaseException; most user-facing ones inherit from Exception.

except with else and finally

The complete try/except/else/finally pattern.

python
import json

def parse_json(text):
    try:
        data = json.loads(text)
    except json.JSONDecodeError as e:
        print(f"  Parse error: {e.msg}")
        return None
    except TypeError:
        print("  Input must be a string")
        return None
    else:
        print(f"  Parsed successfully: {type(data).__name__}")
        return data
    finally:
        print("  Cleanup done")

print("Test 1:")
parse_json('{"key": "value"}')
print("Test 2:")
parse_json("not json {")
print("Test 3:")
parse_json(None)

else runs only when no exception occurred. finally runs always. Together they create a complete error handling pattern.

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