This document provides an overview of key concepts in Python programming including: - The IDLE integrated development environment and print statement syntax. - Operator precedence and common error messages. - Data types like strings and numeric types. - Relational, logical, and bitwise operators for comparisons. - Variables, keywords, and assignment statements. - Built-in functions, function definition syntax, and calling functions. - Control structures like for loops, if/else conditional statements, and while loops for iteration.

1. P.INDURANI
ASSISTANT PROFESSOR & HEAD
DEPARTMENT OF COMPUTER SCIENCE
PARVATHY’S ARTS AND SCIENCE COLLEGE
DINDIGUL
11
PYTHON
PROGRAMMING

2. UNIT I
Introduction – Interactive programming
language.
IDLE – Integrated Development and Learning
Environment.
• >>> - To indicate waiting for a user command.
• To be printed text is enclosed between
apostrophe marks.
eg: >>> print(‘ Hello World’)
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3. Example
3

4. Operators
Precedence of arithmetic operators
• () Parentheses
• ** Exponentiation
• - Negation
• / division // integer division * multiplication %
modulus
• + addition – subtraction
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5. Error Message
>>> 10+4(3+3)
Traceback (most recent call last):
File "<pyshell#10>", line 1, in <module>
10+4(3+3)
TypeError: 'int' object is not callable
>>> 10/0
Traceback (most recent call last):
File "<pyshell#11>", line 1, in <module>
10/0
ZeroDivisionError: integer division or modulo by zero
>>> 5

6. Python String
Enclosed within single, double or triple quotes.
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7. Relational Operators
• To comparing expression values.
• Yield values: true, false
• ASCII values are used for string comparison
• Does not allow string values to be compared with
numeric values.
Operators are: ==, <, >, <=, >=, !=
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8. Operators
Logical Operators
• Combining expressions
• Yield values: true, false
• Involving arithmetic, relational and logical
operators.
• Evaluation using precedence rules.
– Logical: not, and, or
– Operators: arithmetic, relational, logical
Bitwise Operators – Operate bit by bit
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9. Variables and Assignment
Statements
• Variables are often called names.
• Binds a variable to an object
• Syntax: variable = expression
Rules:
• Must begin with letter or _ underscore
• Contain any number of letters, digits or underscore.
• Python is case sensitive
• More than one variable may refer to the same
object.
• Shorthand Notation: >> a=a+5
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10. Statements
Keywords
• Have special meaning.
• Cannot be used for naming objects.
• Eg: continue, for, while, del, true, def, except,
if, return, and, else, nonlocal, etc.,
Script Mode
• Instruction are written in a file.
• Should have extension .py or .pyw
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11. Example
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12. Functions
To solve a problem divide it into simpler sub programs.
Built-In Functions
• Input – To get user input.
• Eval – evaluating a string
• Composition – Inner function serves as input argument to
outer function.
• Print – printing multiple values in a single call
• Type – determining data type
• Round – rounding to nearest values
• Min and max – Operands must be compatible for comparison
• Pow – Computing power
• Math – import a module before using it.
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13. Function Definition and call
• Comments enhance readability of the code
• Single line comments start with #
• Syntax: def function_name(list_of_parameters):
Eg: def add(a):
• Run - Click run module
• Invoking the function main in the script
Eg: if_name_==‘_main_’:
main()
• The definition of function main
• An if statement
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14. Example
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15. • for loop: Repeats a set of statements over a group of values.
– Syntax:
for variableName in groupOfValues:
statements
• We indent the statements to be repeated with tabs or spaces.
• variableName gives a name to each value, so you can refer to it in
the statements.
• groupOfValues can be a range of integers, specified with the range
function.
Eg: for x in range(1, 6):
print x, "squared is", x * x
Output:
1 squared is 1
2 squared is 4
3 squared is 9
4 squared is 16
5 squared is 25
Control Structures
15

16. The range function specifies a range of integers:
• range(start, stop) - the integers between start (inclusive)
and stop (exclusive)
– It can also accept a third value specifying the change between values.
• range(start, stop, step) - the integers between start (inclusive)
and stop (exclusive) by step
– Example:
for x in range(5, 0, -1):
print x
print "Blastoff!"
Output:
5
4
3
2
1
Blastoff!
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For loop

17. • Some loops incrementally compute a value that is
initialized outside the loop. This is sometimes called
a cumulative sum.
sum = 0
for i in range(1, 11):
sum = sum + (i * i)
print "sum of first 10 squares is", sum
Output:
sum of first 10 squares is 385
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Cumulative loop

18. • if statement: Executes a group of statements only if a
certain condition is true. Otherwise, the statements
are skipped.
– Syntax:
if condition:
statements
• Example:
gpa = 3.4
if gpa > 2.0:
print "Your application is accepted."
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If statement

19. • if/else statement: Executes one block of statements if a certain condition is True, and a
second block of statements if it is False.
– Syntax:
if condition:
statements
else:
statements
• Example:
gpa = 1.4
if gpa > 2.0:
print "Welcome to Mars University!"
else:
print "Your application is denied."
• Multiple conditions can be chained with elif ("else if"):
if condition:
statements
elif condition:
statements
else:
statements
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If…else… statement

20. • while loop: Executes a group of statements as long as a condition is
True.
– good for indefinite loops (repeat an unknown number of times)
• Syntax:
while condition:
statements
• Example:
number = 1
while number < 200:
print number,
number = number * 2
– Output:
1 2 4 8 16 32 64 128
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While