# Python Conditional Statements

Python Conditional Statements, Decision making in Python programming, Python if statement, Python else statement, and Python elif statement.

## Python Language Conditional Statements

Conditional Statements are part of control flow statements in computer programming,

We have three types of Control Flow Statements in Python:
1. Conditional Statements
2. Loop Statements
3. Branching Statements

In Python language also we can find these 3 types of statements…

Generally in any Programming language, conditional Statements are 2 types…
1. If Statement
2. Switch Statement
but in Python no Switch statement, only if the statement

##### Usage of Decision making/Conditional Statements

1. Run a block of statements when a condition is true
2. Run a block of statements when a condition is true, otherwise, run another block of statements
3. Run a block of statements when a compound condition is true
4. Run a block of statements when a compound condition is true, otherwise, run another block of statements
5. Decide among several alternates (elif)
6. Run a block of statements when more than one condition is true (nested if)

1. Run a block of statements when a condition is true

Syntax:

if (condition):
Statement/s
.
.
xxxxxxx

Example:

a=100
b=900

if (a>b):
print(“A is Big Number”)

print(“Hello Python”)

2. Run a block of statements when a condition is true, otherwise, run another block of statements

Syntax:

if (condition):
Statement/s
.
.
else:
Statement/s
.
.
————————-
Example:

a=100
b=900

if (a>b):
print(“A is Big Number”)
else:
print(“B is Big Number”)

print (“Hello Python”)
————————–
a=10.345
b=10.344

if (a>b):
print(“A is Big Number”)
else:
print(“B is Big Number”)
————————
10 > 20
10.234 > 10345
“India” > “China”

ANSI
A to Z (65 to 90)
a to z (97 to 122)
0 to 9 (48 to 57)
—————–
100
“100”
10.23
“10.23”
———————
a=”India”
b=”china”

if (a>b):
print(“India is Big”)
else:
print(“China is Big”)
————————-
a=False
b=True

if (a>b):
print(“A is Big”)
else:
print(“B is Big”)
—————————-
a=100
b=100

if (a>b):
print(“A is Big Number”)
else:
print(“B is Big Number”)

3. Run a block of statements when a compound condition is true

Syntax:

if ((condition1) and “Or” or (condition2)):
Statement/s
.
.
Example:

a=100
b=90
c=80

if ((a>b) and (a>c)):
print (“A is Big Number”)
————————————–
a, b, c =100, 90, 80

if ((a>b) and (a>c)):
print (“A is Big Number”)
———————————–
a, b, c =100, 90, 800

if ((a>b) or (a>c)):
print (“A is Big Number”)

4. Run a block of statements when a compound condition is true, otherwise run another block of statements

Syntax:

if ((condition1) and “Or” or (condition2) and “Or” or (condition3)):
Statements
.
else:
Statement/s
.
——————–
Example:

a=100
b=90
c=800
d=70

if ((a>b) and (a>c) and (a>d)):
print (“A is Big Number”)
else:
print (“A is Not Big Number”)
————————-
a=100
b=90
c=800
d=70

if ((a>b) or (a>c) or (a>d)):
print (“A is Big Number”)
else:
print (“A is Not Big Number”)

5. Decide among several alternates(elif)

Syntax:

if (condition):
Statement(s)
elif (condition):
Statement(s)
elif (condition):
Statement(s)
else:
Statement((s)

Example:
Initialize an Integer Variable and verify the range

If the number is in between 1 and 100 then display “Number is a Small Number”
If the number is in between 101 and 1000 then display “Number is a Medium Number”
If the number is in between 1001 and 10000 then display “Number is a Big Number”
If the number is more than 10000 then display “Number is a High Number”
Otherwise, display “Number is a either Zero or Negative Number”
——————————-
Python Program:

a=0;
if ((a>=1) and (a<=100)):
print (“A is a Small Number”)
elif ((a>100) and (a<=1000)):
print (“A is a Medium Number”)
elif ((a>1000) and (a<=10000)):
print (“A is a Big Number”)
elif (a>10000):
print (“A is a High Number”)
else:
print (“A is either Zero or Negative Number”)

##### 5. Execute a block of Statements when more than one condition is true (Nested if)

syntax:
if (condition){
if (condition){
if (condition){
Statements
————–
————–
}
}
}

Example:
Initialize a, b, c, and d variables (Integer variables), check if the a variable
is bigger than other three variables or not?

a, b, c, d = 100, 90, 70, 500;

if (a>b):
if (a>c):
if (a>d):
print (“A is a Big Number”)
else :
print (“A is Not a Big Number”)
——————————-
a, b, c, d = 100, 909, 70, 50;

if (a>b):
if (a>c):
if (a>d):
print (“A is a Big Number”)
else :
print (“A is Not a Big Number “+ “3rd Condition is not true”)
else :
print (“A is Not a Big Number “+ “2nd Condition is not true”)
else :
print (“A is Not a Big Number “+ “1st Condition is not true”)
——————————-
Using Compound Condition

a, b, c, d = 100, 90, 70, 50;

if ((a>b) and (a>c) and (a>d)):
print (“A is a Big Number”)
else:
print (“A is Not a Big Number”)
——————————-
Nested if Condition vs. Compound Condition

In Nested, if condition we can write multiple else parts, whereas in the compound condition we can write single else part only.

##### Problem: Find the biggest variable (Integer variables) among 4 variables

Use Compound Condition and else if…

a, b, c, d = 100, 90, 70, 50;

if ((a>b) and (a>c) and (a>d)):
print (“A is a Big Number”)
elif ((b>a) and (b>c) and (b>d)):
print (“B is a Big Number”)
elif ((c>a) and (c>b) and (c>d)):
print (“C is a Big Number”)
else:
print (“D is a Big Number”)

Python Conditional Statements