20BCT23 – PYTHON PROGRAMMING.pptx
- 1. 20BCT23 – PYTHON PROGRAMMING
- 2. Literal Constants and Numbers • Literal Constants: – The value of a literal constant can be used directly in programs. – Eg : 7,3,9,’A’ and “Hello” are literal constants. – It is a constant because its value cannot be changed. • Numbers: – Four types of nunmbers in Python. – Integers – 5 or other whole numbers. – Long Integers- 535633629843L or other bigger whole numbers. – Complex Numbers – Number of the form a+bi • Issues in floating point numbers: – The arithmetic overflow problem. – The arithmetic underflow problem. – Loss of precision problem.
- 3. Format() function • format (float(16/(float(3))),’.2f’) – ‘5.33’ • format(float(16/3),’.2f’) – ‘5.33’ • format(3**50,’.5e’) – ‘7.17898e+23’ • format(123456, ’ , ’) – ‘123,456’
- 4. Simple operations on Numbers • 10+7 #17 • 50+40-35 #55 • 12*10 #120 • 96/12 #8.0 • 96//12 #8 • (-30*4)+500 #380 • -15/0 #Zero Division Error • 5*3.0 #15.0 • 78%5 #3 • 152.78//3.0 #50.0 • 152.78/3.0 #2.780000000000001 • 36**0.5 #6.0 • 78//5 #15
- 5. Strings • String are group of characters • Strings can e represented – Using single quotes Eg: ‘Hello’ – Using double quotes Eg: “Hello” same as ‘Hello’ – Using triple quotes – Eg: ‘’’Hello’’’ To specify multi-line. • print(‘Hello’) #Hello • print(“Hello”) #Hello • print(‘ “Hello” ’) #”Hello” • print(“ ‘Hello’ ”) #’Hello’ • print(‘ ’ ’ “Hello” ‘ ‘ ‘) #”Hello” • print(‘’’ ‘Hello’ ’’’) #’Hello’
- 6. Strings • String Literal Concatenation: – print(‘Hello’ ‘ ‘ ‘ World!’) # Hello World! • Unicode Strings: – Standard way of writing international text. – To write text in native language need to enable unicode text editor. – U” Sample Unicode String” # ‘Sample Unicode String’ • Escape Sequence: – Some characters like “, cannot be directly included in a string. – Such characters must be escaped by placing a backslash before them. – Eg: print(‘What’s your Name’) # Invalid Syntax print(‘What’s your Name’) # What’s your Name • Raw String: – In order to specify a string that should not handle any escape sequences and to display exactly as specified raw string. – print(R’What’s Your Name’) # What’s Your Name
- 7. Variable and Identifiers • Variables means its value can vary. • It is just parts of computer’s memory where information is stored. • Variables are reserved memory locations that stores values. • Identifiers are names given to identify something like variables, function, class, module or other object. • Basic rules for naming identifiers, • First character must be an ‘_’ or a letter. • Rest of the identifier can be ‘_’ or letters or numbers. • Identifier names are case sensitive. • Punctuation characters such as @,$ and % are not allowed within identifiers. • Valid: sum, _var,num1,r • Invalid: 1num,my-var,%check
- 8. Data Types • Variable can held values of different types are called data types. • Based on the data types of a variable, the interpreter reserves memory for it and also determines the type of data that can be stored in the reserved memory. – Basic Types: Numbers and Strings – Own Data Type : Classes – Standard Data Type: numbers, string, list, tuple and dictionary.
- 9. Assigning Values to the Variables • Need not explicitly declare variables. • Declaration is done when the value is assigned. • Eg : x=‘a’ • In python, varaibles may be reassigned as many times as possible to change the value stored in them. Val=“hello” print(val) • Multiple Assignment: – Python allows programmers to assign a single value to more than on variables simultaneously. • Eg : sum,a,b,msg=0,3,5,”Result” – Trying to reference a variable that has not been assigned any value causes an error.
- 10. Data Types • Boolean: – Boolean variables have one of the two values. True or False – Eg : Flag=True 20!=20 • Input Operation: – The input function takes user’s input as a string. – Python uses input() functionto take input from user. – Eg: age=input(“Enter Your Age”) • Comments: – Comments are non executable statements in a program. – Makes the program easily readable and understandable by the programmer as well as others who are seeing the code. – # a hash sign represents comment line. – print(“Hello”) #prints the string Hello
- 11. • Reserved Words: – These words have a pre-defined meaning . – Cannot be used for naming identifiers. – Eg : and assert break class exec finally for from not • Indentation: – White space at the beginning of the line is called indentation. – Single tab for each indentation level. – It is used to associate and group statements. – The level of indentation groups statements to form a block of statements. – The statements in a block should have same indentation level. – Error is thrown if indentation is not correct. – Eg : age=21 print(age) # Indentation Error – All the statement inside the block should be at the same indentation level.
- 12. Operators and Expressions • Operators are the constructs that are used to manipulate the value of operands. • Eg: sum=a+b • Arithmetic Operator: • +,-,*,/,//,%,**,|,& • Comparison Operator: – These are also called as relational operator. – Used to compare the values on its either sides and determine the relationship between them. – Eg: a==b a!=b a>b – ==,!=,>,<,>=,<= • Shortcut operators : – +=,-=,*=,/=,%= • Unary operator: – Acts on single operands. – When an operand is preceded by a minus sign, the unary operator negates its value. – Eg : b=-10 a=-b #a=10