Python Flow Control Statement
These statements control the flow of execution of code i.e, they decide which Python instructions to execute next and under which conditions.
Flow Control statements can be categories as:
- Simple If
- If and Else
- Ladder if
- Nested If
Elements of Flow Control
In Python, flow control statements start with the condition and followed by a block of code.
- Conditions: Every flow control statement uses a condition or test expression.
- Blocks of Code: Lines of Python code grouped together in blocks called the clause.
- Indentation: A block of code starts with indentation and ends with the first unindented line.
- Blocks begin when the indentation increases.
- Blocks can contain other blocks.
- Block ends when indentations will be in decreasing order.
○ All boolean expressions are considered as conditions.
○ Condition statements always return the result as True and False.
○ Unlike other programming like C, C++, Java which use braces { } to define a block of code, Python uses indentation.
○ You can also use tab in replacement of space one tab equal to four whitespace
○ There are three rules for blocks:
Python Conditional Statements
- When we write code their chances to raise condition where we need answer in True and False at that condition is called the conditional statement
- The conditional statements provided by Python are:
- If keyword
- Condition
- Colon
- If-else is optionally when if condition is not satisfied then it comes into the if -else clause.
- Else part does not consist the conditions)
- Simple if else Statement: In a simple if else statement there is only one condition that exists, if the condition will be true, then block if will be executed, otherwise the else part will be executed. Let’s see the flow chart of simple if else statement
- Ladder If Statement : In this loop there are more than two condition checked If the condition will not satisfy It check another conscious let’s see the flow chart of the ladder if statement
- Nested If Statement : In this statement every condition consists of another condition whether It is True or False, let’s see the flow chart of the Nested if Statement.
if statement | If statement contain the following syntax
|
if-else statement |
|
Block diagram
Example 1: Program to check whether a number is even and odd.
user=int(input("Enter the Number")) if(user%2==0): print("Even",user)
Output:
==== RESTART: C:/Users/ASUS/AppData/Local/Programs/Python/Python38-32/df.py ==== Enter the Number45 >>> RESTART:C:/Users/ASUS/AppData/Local/Programs/Python/Python38-32/df.py Enter the Number44 Even 44 >>> ======= RESTART: C:/Users/ASUS/AppData/Local/Programs/Python/Python 38-32/df.py ====== Enter the Number40 Even 40 >>>
Example 2: Program to check whether a number is even or odd.
user=int(input("Enter the Number")) if(user%2==0): print(user,"is even") else: print(user,"is odd")
Output:
==== RESTART: C:/Users/ASUS/AppData/Local/Programs/Python/Python38-32/df.py ==== Enter the Number56 56 is even >>> ==== RESTART: C:/Users/ASUS/AppData/Local/Programs/Python/Python38-32/df.py ==== Enter the Number88 88 is even >>> ==== RESTART: C:/Users/ASUS/AppData/Local/Programs/Python/Python38-32/df.py ==== Enter the Number45 45 is odd >>>
Example 3: Program to check the greatest of three numbers.
ram=int(input("Ram")) shyam=int(input("Shyam")) mohan=int(input("Mohan")) if(ram>shyam): if(ram>mohan): print("Ram is oldest") else: print("Mohan is oldest") else: if(shyam>mohan): print("Shyam is oldest") else: print("Mohan is oldest")
Output:
==== RESTART: C:/Users/ASUS/AppData/Local/Programs/Python/Python38-32/df.py ==== Ram56 Shyam54 Mohan21 Ram is oldest >>> ==== RESTART: C:/Users/ASUS/AppData/Local/Programs/Python/Python38-32/df.py ==== Ram55 Shyam60 Mohan33 Shyam is oldest >>> ==== RESTART: C:/Users/ASUS/AppData/Local/Programs/Python/Python38-32/df.py ==== Ram60 Shyam66 Mohan70 Mohan is oldest >>>
Conditional Statement Program (Mini Project)
import random name=input("Name : -") user=eval(input("Username ")) pas=eval(input("Password ")) wpas=eval(input("Re-Enter Password")) roll=random.randint(11,99) if(pas==wpas): print("Hello",name,"You have Successfully Created your roll is ",roll) print("*************************************************************") print("*****************Login******************************") luser=eval(input("Username or Roll Number : - ")) lpass=eval(input("Password : - ")) if(luser==user or luser==roll and lpass==pas): print("You Have Successfully Login\nName : ",name,"\t\tRoll mber",roll) print("\nPlease Enter your subject marks") hin=int(input("Hindi : ")) eng=int(input("English : ")) math=int(input("Math : ")) sci=int(input("Science : ")) com=int(input("Computer : ")) total=hin+eng+math+sci+com per=total/5 print("Total : ",total) print("Percentage :",per) if(per>75): print("Grade : A+") elif(per<75 and per>60): print("Grade : A") elif(per<60 and per>50): print("Grade :B") elif(per<50 and per>45): print("Grade :C") else: print("Grade : Fail") else: print("Wrong information Provide") else: print("Password are not Match")
Output
Name : -Amit Username "amt" Password 1234 Re-Enter Password1234 Hello Amit You have Successfully Created your roll is 50 ************************************************************* *****************Login****************************** Username or Roll Number : - 50 Password : - 1234 You Have Successfully Login Name : Amit Roll number 50 Please Enter your subject marks Hindi : 45 English : 54 Math : 33 Science : 67 Computer : 43 Total : 242 Percentage : 48.4 Grade :C