Tamilnadu Samacheer Kalvi 12th Computer Science Notes Chapter 6 Control Structures Notes
Control structure:
A program statement that causes a jump of control from one part of the program to another is called control structure or control statement.
Control Structures in Python:
There are three important control structures namely
- Sequential
- Alternative or Branching
- Iterative or Looping
Sequential Statement:
A sequential statement is composed of a sequence of statements which are executed one after another. A code to print your name, address and phone number is an example of sequential statement.
Alternative or branching statements in Python:
The types of alternative or branching statements provided by Python are:
- Simple if statement
- if..else statement
- if..elif statement
i) Simple if statement
Simple if is the simplest of all decision making statements. Condition should be in the form of relational or logical expression.
Syntax:
if:<condition>:
statements-block1
(ii) if..else statement
The if ..else statement provides control to check the true block as well as the false block. Following is the syntax of ‘if..else’ statement.
Syntax:
if:<condition>:
statements-block 1
else:
statements-block 2
iii) if..else statement
The if ..else statement provides control to check the true block as well as the false block. Following is the syntax of ‘if..else’ statement.
Syntax:
if:<condition>:
statements-block 1
else:
statements-block 2
Iteration or Looping constructs :
- Iteration or loop are used in situation when the user need to execute a block of code several of times or till the condition is satisfied.
- A loop statement allows to execute a statement or group of statements multiple times.
Looping constructs in Python:
Python provides two types of looping constructs:
- while loop
- for loop
1. While loop:
Syntax:
while< condition > :
statements block 1
[else:
statements block 2]