CLASS -11 COMPUTER SCIENCE
CHAPTER- 6 DEBUGGING PROGRAMS
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NOTES FOR COMPLETE UNDERSTANDING -
- Always whenever we create a program there might be some errors in it.
- And a programmer needs to find these errors and should fix
them to make the program error free. This is referred as debugging.
- What is Debugging?
- It is the procedure of searching errors, their reasons of occurrence and scientific procedure of their
fixation.
- ERRORS and EXCEPTION :
- Errors and Exception, both disturbs the Execution of Program .
- Errors, usually pop out at the time of translation.
- While, Exception gets generated during program running , due to an
input.
- An error is often referred as a bug .
- It is a code
that prevents a program from running successfully and correctly .
- Some errors are less dangerous in nature whereas some
are very trachareous. Some errors are very burdensome to find.
- Errors are of 3 types namely – • Compile Time Error • Run Time Error • Logical Error
- Compile Time Error :
- Errors are of basically 2 types – • Syntax Error : Violation of formal protocols of a programming
language results in syntax error.
For eg. x=(x*y) • Semantics Error: keyword Semantics refers to the set of protocols which sets the meaning of statements. A senseless statement results in semantics
error.
For eg. x * y = z
- Logical Error :
- If a program is not giving expected output and also not showing any other error it may be possible that
program is having a logical error. This error generates
due to wrong implication thought by programmer. For eg- • To use a variable without initialising value. • To provide wrong parameters to any function.
- Run Time Error :
- These errors generates during a program execution .
- These errors are hard to find out.
- Some run time errors obstructs a program from execution
which is known as program crash or abnormal termination of
program.
- Many run time errors like infinite loop or wrong value are easier to detect.
- It is important to safeguard a program from getting crashed in case of
run time error. A program should be robust.
- Exception:
- Exception is a stage when a program ends abnormally
and it cannot be controlled.
For eg. -
• a=10 • b=0 • c=a/b -----> (Mathematical Exception) – Inputting wrong account number in an ATM is
an error. – But receiving less/more amount than expected is an
Exception . An exception cause unexpected ending of a program.
- Exception Handling in Python :
- try and except clauses are good tools to handle an
exception. Any block which has the probability of occurring an
exception, that block is to be written under try clause and the
code to handle the exception is to be written under except
clause. Syntax is as under : try: # code with max possibility of exception will be written here. except: #code to handle above exception will be written here.
- Some Built-in exceptions:
