Programming Basics: Loops, Selection & Examples

1️⃣ WHILE and FOR Loop Example

Pseudocode

WHILE NotSolved
    Instructions here
    FOR i ← 1 TO 5
        Instructions here
    ENDFOR
    Instructions here
ENDWHILE

Equivalent Python Code

NotSolved = True  # You can change this condition as needed

while NotSolved:
    # Instructions here
    print("Doing something before the loop")

    for i in range(1, 6):  # 1 to 5 inclusive
        # Instructions inside FOR loop
        print(f"Iteration {i} inside FOR loop")

    # Instructions after FOR loop
    print("Doing something after the loop")

    # Example condition to stop the while loop
    NotSolved = False  # Change this when the problem is solved

✅ Explanation:

while NotSolved: → Keeps looping until NotSolved becomes False.
for i in range(1, 6): → Loops from 1 to 5 inclusive.
Indentation defines which statements belong to each block.

2️⃣ IF Statement Example (Nested Selection)

Pseudocode

IF GameWon THEN
    Instructions here
    IF Score > HighScore THEN
        Instructions here
    ENDIF
    Instructions here
ENDIF

Equivalent Python Code

GameWon = True       # Example condition
Score = 120
HighScore = 100

if GameWon:
    # Instructions here
    print("You won the game!")

    if Score > HighScore:
        # Instructions inside the nested IF
        print("New high score!")
        HighScore = Score

    # Instructions after the nested IF
    print("Returning to main menu...")

✅ Explanation:

if GameWon: → Outer condition checks if the game is won.
if Score > HighScore: → Inner condition only runs if the outer one is true.
Indentation defines which block belongs to which if.

3️⃣ Understanding Selection in Programming

What is Selection?

Selection means making decisions in a program — choosing which part of the code to run based on a condition. It allows the program to select different paths of execution depending on whether something is True or False.

In simple terms:

Selection = Decision-making (using IF statements or similar).

Examples of Selection in Python

Example 1: Simple IF Statement

score = 85

if score >= 50:
    print("You passed!")

Example 2: IF ... ELSE

score = 45

if score >= 50:
    print("You passed!")
else:
    print("You failed.")

Example 3: IF ... ELIF ... ELSE

score = 75

if score >= 90:
    print("Grade: A")
elif score >= 70:
    print("Grade: B")
else:
    print("Grade: C")

How Selection Fits with Other Statement Types

Type	What it does
Variable declaration	Create storage for data (`score = 0`)
Constant declaration	Store fixed values (`PI = 3.14159`)
Assignment	Change a variable’s value (`score = 10`)
Iteration	Repeat actions (`for`, `while`)
Selection	Choose actions (`if`, `else`)
Subroutine	Group actions (`def function():`)

Example Combining Them All

PI = 3.14159            # constant declaration
radius = 5              # variable declaration
area = PI * radius**2   # assignment

def display_area(area): # subroutine
    print("Area:", area)

if area > 50:           # selection
    print("Big circle!")
else:
    print("Small circle!")

for i in range(3):      # iteration
    display_area(area)