Strings and Loops in Python

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String

Strings are sequence of characters written inside quotes. It can include letters, numbers, symbols and spaces. Python does not have a separate character type.
Strings are immutable, meaning their values cannot be changed after creation. Any modification to a string creates a new string instead of altering the original one.

Common String Methods

Python string methods is a collection of in-built Python functions that operates on strings.

upper()
lower()
find()
split()
strip()
format()
join()

Discussed problems

Reverse a String
Password Authentication
Parse csv "java","1","2","3".."6"
Convert uppercase to lowercase

Examples

Parse csv "java","1","2","3".."6"

data = input("Enter CSV data: ")
values = data.split(",")
total = 0
for i in values:
    i = i.strip('"')
    if i.isdigit():
        total += int(i)

print("Total =", total)

Input-"java","1","2","3","4","5","6"

Output-Total = 21

Loop

Loops are used to execute a block of code repeatedly until a condition is met or all items in a sequence are processed. The main types are For loops (iterating over sequences) and While loops (executing code based on a condition).
break is used to exit a for loop or a while loop, whereas continue is used to skip the current block, and return to the "for" or "while" statement.

While Loop Syntax

while condition:
statement

For Loop Syntax

for variable in range(start, stop, step):
statement

Discussed problems

Sum of (N) numbers
Multiplication table
Print even numbers

Examples
Sum of (N) numbers

def sum_of_numbers(n):
    i=1
    sum=0
    while i<=n:
        sum+=i
        i+=1
    print("The sum of first",n,"numbers is:",sum)

n=int(input("Enter the number of terms: "))
sum_of_numbers(n)