Syntax Error
Runtime Error
Logical Error
Typo or improper use of code.
Compiler or interpreter will alert you prior to execution.
ie. Missing colon for a definition
#!/usr/bin/python3
# This program divides two numbers
# The function below calculates and returns the division result
def div(x,y,z)
q = x/y
return q
# Main portion of program to set up the problem
a = int(input("Enter the first operand: "))
b = int(input("Enter the second operand: "))
c = div(a,b)
print("\nYour answer is %d\n" % c)Illegal implementation of code or routine, though syntactically correct.
Caught during execution, program will immediately crash or exit.
ie. Wrong number of function arguments
#!/usr/bin/python3
# This program divides two numbers
# The function below calculates and returns the division result
def div(x,y,z):
q = x/y
return q
# Main portion of program to set up the problem
a = int(input("Enter the first operand: "))
b = int(input("Enter the second operand: "))
c = div(a,b)
print("\nYour answer is %d\n" % c)Execution completes without error, but behavior or results are unexpected.
ie. Wrong format string identifier
#!/usr/bin/python3
# This program divides two numbers
# The function below calculates and returns the division result
def div(x,y):
q = x/y
return q
# Main portion of program to set up the problem
a = int(input("Enter the first operand: "))
b = int(input("Enter the second operand: "))
c = div(a,b)
print("\nYour answer is %d\n" % c)A user may type whatever they like into a keyboard.
If their input is of an unexpected form, errors may occur
ie. Failure to account for user malice
#!/usr/bin/python3
# This program divides two numbers
# The function below calculates and returns the division result
def div(x,y):
q = x/y
return q
# Main portion of program to set up the problem
a = int(input("Enter the first operand: "))
b = int(input("Enter the second operand: "))
c = div(a,b)
print("\nYour answer is %f\n" % c)White Box
Black Box
Source Code Review
Some hacker has messed up my beautiful restaurant seating program!
Please, find all the bugs and make our business operational again!
Print Statements
Return to interpreter
python -i
Using a Debugger
Static Analysis
...on source code
Static Analysis
...on binary
decompile .pyc files
Fuzzing
Discuss!