Selection: if, elif, else Statements

This lesson covers selection (also called branching or conditional statements) as required by OCR J277 Section 2.3. Selection allows a program to make decisions and execute different blocks of code depending on whether a condition is true or false.

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What Is Selection?

Selection is a programming construct that allows the program to choose between different paths of execution based on a condition. Without selection, programs would always execute the same instructions in the same order, regardless of input.

The three main selection structures in OCR pseudocode are:

1. if...then...endif — execute code if a condition is true
2. if...then...else...endif — choose between two paths
3. if...then...elseif...else...endif — choose between multiple paths

The following flowchart shows how if/elseif/else selection works:

flowchart TD
    A([Start]) --> B{Condition 1\ntrue?}
    B -- Yes --> C["Execute\nif block"]
    B -- No --> D{Condition 2\ntrue?}
    D -- Yes --> E["Execute\nelseif block"]
    D -- No --> F["Execute\nelse block"]
    C --> G([Continue])
    E --> G
    F --> G

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Simple if Statement

Executes a block of code only if the condition is true.

OCR Pseudocode:

age = int(input("Enter your age: "))
if age >= 18 then
    print("You are an adult")
endif

Python:

age = int(input("Enter your age: "))
if age >= 18:
    print("You are an adult")

If the condition is false, nothing happens — the program continues to the next line after endif.

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if...else Statement

Chooses between two paths: one if the condition is true, another if it is false.

OCR Pseudocode:

mark = int(input("Enter your mark: "))
if mark >= 50 then
    print("Pass")
else
    print("Fail")
endif

Python:

mark = int(input("Enter your mark: "))
if mark >= 50:
    print("Pass")
else:
    print("Fail")

OCR Exam Tip: In OCR pseudocode, you must include then after the condition and endif to close the block. Forgetting endif is a common mistake that will lose marks.

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if...elseif...else Statement

Chooses between multiple paths by checking conditions in order.

OCR Pseudocode:

mark = int(input("Enter your mark: "))
if mark >= 90 then
    print("Grade A*")
elseif mark >= 80 then
    print("Grade A")
elseif mark >= 70 then
    print("Grade B")
elseif mark >= 60 then
    print("Grade C")
elseif mark >= 50 then
    print("Grade D")
else
    print("Grade U")
endif

Python:

mark = int(input("Enter your mark: "))
if mark >= 90:
    print("Grade A*")
elif mark >= 80:
    print("Grade A")
elif mark >= 70:
    print("Grade B")
elif mark >= 60:
    print("Grade C")
elif mark >= 50:
    print("Grade D")
else:
    print("Grade U")

How It Works