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Sequence And Selection Edexcel

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Exam code:1CP2

Sequence

What is sequence?

Sequence is a set of instructions executed one after another

Python example
`def calculate_area(length, width):` “”” This function calculates the area of a rectangle Inputs: length: The length of the rectangle width: The width of the rectangle Returns: The area of the rectangle “”” # Calculate area `return area` `area = length * width` # ————————————————————————# Main program # ———————————————————————— `length = 5` `width = 3` `correct_area = calculate_area(length, width)` `print(f"Correct area (length * width): {correct_area}")`

Python example

def calculate_area(length, width):

“””

This function calculates the area of a rectangle

Inputs:

length: The length of the rectangle

width: The width of the rectangle

Returns:

The area of the rectangle

“””

# Calculate area

return area

area = length * width

# ————————————————————————# Main program

# ————————————————————————

length = 5

width = 3

correct_area = calculate_area(length, width)

print(f"Correct area (length * width): {correct_area}")

In the example, the sequence of instructions is wrong and would cause a runtime error (opens in a new tab)
In the calculate_area() function a value is returned before it is assigned
The correct sequence is:

# Calculate area
area = length * width
return area

Selection

What is selection?

Selection is a programming construct that allows a program to execute in different ways based on the outcome of a condition
Selection is implemented using the if function
Nested selection can be used, the use of ‘else‘ and ‘elif‘ is preferable for efficiency and to make logic clearer

Python examples
`age = 18` `if age >= 18:` `print("You are eligible to vote")` `else:` `print("You are not eligible to vote")`
`grade = 85` `if grade >= 90:` `print("Excellent!")` `elif grade >= 80:` `print("Very Good!")` `else:` `print("Good luck next time!")`
Nested selection `is_registered = True` `has_paid = False` `if is_registered:` `if has_paid:` `print("You can access the course materials")` `else:` `print("Please complete your payment to access materials")` `else:` `print("Please register for the course first")`

Python examples

age = 18
if age >= 18:
print("You are eligible to vote")
else:
print("You are not eligible to vote")

grade = 85

if grade >= 90:

print("Excellent!")

elif grade >= 80:

print("Very Good!")

else:

print("Good luck next time!")

Nested selection

is_registered = True

has_paid = False

if is_registered:

if has_paid:

print("You can access the course materials")

else:

print("Please complete your payment to access materials")

else:

print("Please register for the course first")

Computer Science GCES EDEXCEL

Sequence And Selection Edexcel

Sequence

What is sequence?

Selection

What is selection?

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