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Lecture 1 : Syntax

User input and output

string input

input_str = input("enter string:")
print(input_str)
print(type(input_str)) # str

hello
<class 'str'>

bool

is_male = True
print(type(is_male))

<class 'bool'>

NoneType

empty_value = None
print(type(empty_value))

<class 'NoneType'>

integer input

input_int= int(input("enter num:")) 
print(input_int)
print(type(input_int)) # int

5
<class 'int'>

array input

input_list_str = input("enter list with spaces:")
print(input_list_str)
input_list_str_array = input_list_str.split(" ")
print(input_list_str_array)
input_list_map = map(int,input_list_str_array)
input_list = list(input_list_map)

print(input_list)

1 2 3
['1', '2', '3']
[1, 2, 3]

Data Types

int

age = 25
print(type(age))

<class 'int'>

float

height = 5.9
print(type(height))

<class 'float'>

str

name = "piyush"
print(type(name))

<class 'str'>

list

fruits = ["apple", "mango","banana"] 
print(type(fruits))

<class 'list'>

tuple

coordinates = (10,20)
print(type(coordinates))

<class 'tuple'>

dict

person = {
    "name":"Piyush",
    "age":30,
    "height" :6.1,
    "languages":["english","hindi"]
}
print(type(person))

<class 'dict'>

set

unique_numbers = {1,2,3,4,5}
print(type(unique_numbers))

<class 'set'>

If Else Statements

marks = 55
if marks < 40:
    print("F")
elif marks >=40 and marks < 60:
    print("C")
elif marks >=60 and marks < 80:
    print("B")
elif marks >=80 and marks < 90:
    print("A")
else:
    print("A+")

C

Switch Statements

day =4
match day:
    case 1: 
        print("Monday")
    case 2: 
        print("Tuesday")
    case 3: 
        print("Wednesday")
    case 4: 
        print("Thursday")
    case 5: 
        print("Friday")
    case 6: 
        print("Saturday")
    case 7: 
        print("Sunday")
    case _:
        print("invalid day")

Thursday

Loops

1D iteration

num = 5
for i in range(1,11):
    print(f"{num} x {i} = {num * i}")

5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
5 x 4 = 20
5 x 5 = 25
5 x 6 = 30
5 x 7 = 35
5 x 8 = 40
5 x 9 = 45
5 x 10 = 50

2D Iteration

tables = [2,3]
for num in tables:
    for i in range(1, 11):
        print(f"{num} x {i} = {num * i}")
    print("")

2 x 1 = 2
2 x 2 = 4
2 x 3 = 6
2 x 4 = 8
2 x 5 = 10
2 x 6 = 12
2 x 7 = 14
2 x 8 = 16
2 x 9 = 18
2 x 10 = 20

3 x 1 = 3
3 x 2 = 6
3 x 3 = 9
3 x 4 = 12
3 x 5 = 15
3 x 6 = 18
3 x 7 = 21
3 x 8 = 24
3 x 9 = 27
3 x 10 = 30

While Loops

my_list = [1,2,3,4,5,6,7,9]
target = 7

idx =0
while idx < len(my_list):
    num = my_list[idx]
    if num == target:
        print(f"{target} found at index {idx}")
    idx +=1
print(f"{target} not found")

7 found at index 6
7 not found

Functions

Pass by value

• int, float , bool , str

def modifyVal(age,name,height,is_male):
    age = 0
    name = ""
    height = 0.0
    is_male =False

age = 31
name = "piyush"
height = 6.1
is_male = True

modifyVal(age,name,height,is_male)
print(age,name,height,is_male)

31 piyush 6.1 True

Pass by reference

• dict, list ,

def modifyVal(person):
    person["age"] = 0
    person["name"] =""
    person["height"] = 0.0
    person["is_male"] = False

person = {
    "name": "Piyush",
    "age":31,
    "height":6.1,
    "is_male" :True

}

modifyVal(person)
print(person)

{'name': '', 'age': 0, 'height': 0.0, 'is_male': False}

Mathematical Operations

import math
print(math.log(1000,10))
print(int(math.log(1000,10)))

print(math.pow(10,3))
print(10 ** 3)

print(abs(-100))

print(math.floor(100.7) )
print(math.ceil(100.7) )

2.9999999999999996
2
1000.0
1000
100
100
101

Strings

Modify the existing string

str is immutable

• first convert into list
• then update the value
• convert the list into str

s = "hello"
s_list = list(s)

s_list[0] = "H"
s = "".join(s_list)

s += "I"
print(s)

HelloI

Accessing index and char in a single iteration

s = "hello"

for i , ch in enumerate(s):
    print("i",i)
    print("ch",ch)

i 0
ch h
i 1
ch e
i 2
ch l
i 3
ch l
i 4
ch o

Splitting the strings into words by spaces

• It handles multiple spaces too

print("piyush is best".split()) 
print(" preeti is  very  good   ".split())

['piyush', 'is', 'best']
['preeti', 'is', 'very', 'good']

Classes

Defining a class

class Person:
    def __init__(self,name):
        self.name = name
        self.age = None

    def set_age(self,age):
        self.age = age

person = Person("piyush")
print(person.name)
print(person.age)

person.set_age(31)
print(person.age)

piyush
None
31