This document discusses iteration and looping constructs in Python. It covers: - The while loop, which repeatedly executes a block of code as long as a condition is true. The condition is checked before and after each iteration. - The for loop, which iterates over items in a sequence. It uses a variable to take the value of each item and continues until the last item is reached. - The range() function, which generates a sequence of numbers for use in for loops. It can specify the start, end, and increment size to control the sequence generated. Nested loops and examples of while and for loops printing numbers are also demonstrated.

1. ITERATION in PYTHON
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2. ITERATION
• Repeated execution of a set of statements is called
iteration.
• Most commonly syntax are for and constructs
• In for, the number of repetitions is specified explicitly
in advance
• In while, the code block executes until some condition
is met.

3. The While construct
• The while statement allows you to repeatedly execute a block of statements as long as a condition is true.
• Syntax
while (condition):
Body of while
• Test expression is checked first.
• The body of the loop is entered only if the condition is True.
• After one iteration, the test expression is checked again.
• This process continues until the condition becomes False.
• Body starts with indentation

4. The While loop

5. While loop - Example
Program to print numbers from 1 to 5
Output : 1 2 3 4 5

6. The for loop
Syntax
for val in sequence:
Body of for
• val is the variable that takes the value of the item
inside the sequence on each iteration.
• Loop continues until we reach the last item in the
sequence.
• The body of for loop is separated from the rest of the
code using indentation.

7. For Loop

8. Program to print first 5 numbers
number = 5;
for i in range(1,number+1):
print (i, end=' ‘);
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9. For loop - Example
• Program to find the sum of first 10 numbers using
range function
number = int(input("Enter any Number: "))
sum = 0
for value in range(1, number + 1):
sum = sum + value
print("The Sum of Numbers = ", sum))

10. The range ( ) function
• To loop through a set of code a specified number of times, we can use the range()function,
• The range() function returns a sequence of numbers, starting from 0 by default, and increments
by 1 (by default), and ends at a specified number.
• We can also define the start, end and step size as range(start,end,step size) – the last value will
be always end -1
• •range(5)will generate numbers from 0 to 4
• •range(2, 6) will generate numbers : 2, 3, 4, 5
• •range(1, 10, 2) will generate numbers : 1, 3, 5, 7, 9
• •range(5, 0,-1) will generate numbers : 5, 4, 3, 2, 1

11. Example : for loop
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12. Example : for loop
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13. Nested for loop
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• Nested for loop – find the output of the below codes: