Else–if ladder in C++ - Step-by-Step Execution

Concept Flow - Else–if ladder

Start

↓

Check condition1

|Yes↓

Execute block1

↓

End

No↓

Check condition2

|Yes↓

Execute block2

↓

End

No↓

Check condition3

|Yes↓

Execute block3

↓

End

No↓

Execute else block

↓

End

The program checks each condition in order. When one condition is true, it runs that block and skips the rest. If none are true, it runs the else block.

Execution Sample

C++

int x = 15;
if (x < 10) {
  std::cout << "Less than 10";
} else if (x < 20) {
  std::cout << "Less than 20";
} else {
  std::cout << "20 or more";
}

Checks x against conditions and prints which range it falls into.

Execution Table

Step	Condition Checked	Condition Result	Branch Taken	Output
1	x < 10	False	No
2	x < 20	True	Yes	Less than 20
3	Else block	Skipped	No
4	End	N/A	Program ends

💡 Condition x < 20 is true, so the corresponding block runs and the ladder ends.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
x	15	15	15	15

Key Moments - 2 Insights

Why does the program skip checking the else block after a true condition?

Because once a true condition is found (see Step 2 in execution_table), the program runs that block and exits the else-if ladder immediately.

What happens if all conditions are false?

The else block runs (Step 3 would be 'Yes'), providing a default action when no conditions match.

Visual Quiz - 3 Questions

Look at the execution table, what is the output at Step 2?

A Less than 10

B 20 or more

C Less than 20

D No output

💡 Hint

Check the 'Output' column at Step 2 in the execution_table.

At which step does the program stop checking further conditions?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Branch Taken' column to see when a condition is true and the ladder ends.

If x was 25, which step would produce output?

A Step 3

B Step 2

C Step 1

D Step 4

💡 Hint

Refer to the conditions and see which block runs when all conditions fail except else.

Concept Snapshot

Else–if ladder syntax:
if (condition1) { ... }
else if (condition2) { ... }
else { ... }

Checks conditions top to bottom.
Runs first true block only.
Else runs if none true.

Full Transcript

This example shows an else-if ladder in C++. The program checks if x is less than 10. If not, it checks if x is less than 20. If that is true, it prints 'Less than 20' and stops checking further. If none of the conditions are true, it runs the else block. Here, x is 15, so the second condition is true and the output is 'Less than 20'.