String Methods, Conditional Statements (if/elif/else), Loops (for, range())

🐍 Python for DevOps — Class 5 Notes Topic: String Methods, Conditional Statements ( if/elif/else ), Loops ( for , range() ) 📌 Key Concepts Overview Concept One-Line Definition String Methods Built-in functions to inspect and transform strings if / elif / else Execute code blocks based on conditions for loop Iterate over any iterable — string, list, range, dict range() Generate a sequence of numbers to loop over Nested if An if block inside another if block Nested for A for loop inside another for loop 🔤 Part 1 — String Methods (Continuation from Class 4) Checking String Case # islower() — True if ALL characters are lowercase ' devops ' . islower () # True ' Devops ' . islower () # False # isupper() — True if ALL characters are uppercase ' DEVOPS ' . isupper () # True ' Devops ' . isupper () # False # Practical: normalize before comparing env = input ( ' Enter environment: ' ) if env . lower () == ' production ' : print ( ' ⚠️ Deploying to PROD! ' ) Checking Digit / Numeric Strings Method Accepts Rejects DevOps Use isdecimal() 0-9 only decimals, superscripts Port validation isdigit() 0-9 + superscripts decimal points Version numbers isnumeric() 0-9 + superscripts + fractions decimal points Broadest check # Key difference — decimal point breaks all three ' 8080 ' . isdecimal () # True ' 8080 ' . isdigit () # True ' 8080 ' . isnumeric () # True ' 80.80 ' . isdecimal () # False — dot is not a digit ' 80.80 ' . isdigit () # False ' 80.80 ' . isnumeric () # False # DevOps use: validate user input before casting port_input = input ( ' Enter port: ' ) if port_input . isdecimal (): port = int ( port_input ) else : print ( ' ❌ Invalid port — must be a whole number ' ) replace() — Find and Replace in Strings # str.replace('old', 'new') ' Python ' . replace ( ' P ' , ' J ' ) # 'Jython' ' prod-server-01 ' . replace ( ' - ' , ' _ ' ) # 'prod_server_01' ' This is python class ' . replace ( ' i ' , ' a ' ) # 'Thas as python class' — ALL occurrences # DevOps: sanitize strings for us