Nested conditional statements in C++ - Step-by-Step Execution

Concept Flow - Nested conditional statements

Start

↓

Check Condition 1

|Yes↓

Check Condition 2

|Yes↓

Execute Block A

↓

End

No↓

Execute Block B

↓

End

No↓

Execute Block C

↓

End

First, check the outer condition. If true, check the inner condition. Depending on inner condition, run one block. If outer condition is false, run another block.

Execution Sample

C++

#include <iostream>
int main() {
  int x = 10;
  if (x > 5) {
    if (x < 15) std::cout << "A";
    else std::cout << "B";
  } else {
    std::cout << "C";
  }
  return 0;
}

This code checks if x is greater than 5, then checks if x is less than 15, printing A, B, or C accordingly.

Execution Table

Step	Condition Checked	Condition Result	Branch Taken	Output
1	x > 5	true	Enter first if
2	x < 15	true	Enter nested if	A
3	End	-	-	Program ends

💡 x is 10, so x > 5 is true and x < 15 is true, output 'A' and program ends

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
x	10	10	10	10

Key Moments - 2 Insights

Why does the program print 'A' and not 'B' or 'C'?

Because at Step 1, x > 5 is true, so it enters the first if. Then at Step 2, x < 15 is true, so it prints 'A' and skips the else blocks. See execution_table rows 1 and 2.

What happens if the outer condition is false?

If x > 5 was false, the program would skip the nested if and print 'C' from the else block. This is shown in the concept_flow where the outer condition leads to a different branch.

Visual Quiz - 3 Questions

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

A "C"

B "A"

C "B"

D No output

💡 Hint

Check the 'Output' column in execution_table row 2.

At which step does the program decide not to execute the else block?

A Step 2

B Step 1

C Step 3

D No else block executed

💡 Hint

Look at the 'Branch Taken' column in execution_table rows 1 and 2.

If x was 20, what would be the output according to the execution flow?

A "A"

B "C"

C "B"

D No output

💡 Hint

If x=20, x > 5 is true but x < 15 is false, so nested else prints 'B'.

Concept Snapshot

Nested conditional statements check one condition inside another.
Syntax:
if (condition1) {
  if (condition2) {
    // code A
  } else {
    // code B
  }
} else {
  // code C
}
The inner if runs only if outer if is true.
Else blocks run if their conditions fail.

Full Transcript

This example shows nested conditional statements in C++. First, the program checks if x is greater than 5. If yes, it checks if x is less than 15. If both are true, it prints 'A'. If the second condition is false, it prints 'B'. If the first condition is false, it prints 'C'. The execution table traces these steps clearly. Variable x remains 10 throughout. Key moments clarify why 'A' is printed and what happens if conditions change. The quiz tests understanding of output and branching decisions.