**Python Conditional Statements**

1) Execute a block of Statements when condition is true.

2) Execute a block of Statements when a compound condition is true.

3) Execute a block of Statements when condition is true otherwise execute another block of Statements

4) Decide among several alternates(elif)

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

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

*Control Flow Statements*1) Conditional Statements

2) Loop Statements

3) Branching Statements

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

Generallly in any Programming langguage conditional Statements are 2 types...

1) If Statement

2) Switch Statement

but in Python no Switch statement, only if statement

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**Usage of Conditional Statements / Decision Making Statements**

1) Execute a block of Statements when condition is true.

**Syntax:**

if (Condition/Expression):

Statement(s);

**Example:**

a, b = 100, 50;

if (a>b):

print ("A is a Big Number");

a, b = 100, 50;

if (a>b):

print ("A is a Big Number");

print ("Hello Python");

-------------------------------

2) Execute a block of Statements when a compound condition is true

**Syntax:**

if ((condition1/Expression1) and (Condition2/Expression2)) :

Statement(s);

**Example:**

a, b, c = 100, 50, 700;

if ((a>b) or (a>c)):

print ("A is a Big Number");

-------------------------------

3) Execute a block of Statements when condition is true otherwise execute another block of Statements

**Syntax:**

if (Condition):

Statement(s);

else:

Statement(s);

**Example:**

a, b = 100, 200;

if (a>b):

print ("A is a Big Number");

else :

print ("B is a Big Number");

-------------------------------

4) 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"

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**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");

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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");

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Nested if Condition vs. Compound Condition

In Nested if condition we can write multiple else parts, where as in Compound

Condition we can write single else part only.

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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");

-------------------------------

Also Read:

**1)***In Which sequence should We learn Python?*

__2) Introduction to Python__

__3) Download & Install Python__

__4) Variables and Data Types in Python__

__5) Python Operators__
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