If–else statement in C++ - Step-by-Step Execution

Concept Flow - If–else statement

Start

↓

Evaluate condition

↓

Execute if-block

↓

End

↓

Execute else-block

↓

End

The program checks a condition. If true, it runs the 'if' part; if false, it runs the 'else' part, then ends.

Execution Sample

C++

#include <iostream>
using namespace std;

int main() {
  int x = 10;
  if (x > 5) {
    cout << "Big";
  } else {
    cout << "Small";
  }
  return 0;
}

Checks if x is greater than 5; prints 'Big' if true, otherwise 'Small'.

Execution Table

Step	Condition (x > 5)	Result	Branch Taken	Output
1	10 > 5	true	if-block	"Big"
2	-	-	End	-

💡 Condition true, executed if-block, then program ends.

Variable Tracker

Variable	Start	After Step 1	Final
x	10	10	10

Key Moments - 2 Insights

Why does the program print "Big" and not "Small"?

Because the condition x > 5 is true at step 1, so the if-block runs and else-block is skipped.

What happens if the condition is false?

The else-block runs instead, printing "Small" as shown in the branch taken column if condition was false.

Visual Quiz - 3 Questions

Look at the execution table, what is the output at step 1?

A "Small"

B "Big"

C No output

D Error

💡 Hint

Check the Output column at step 1 in the execution_table.

At which step does the program decide which branch to take?

A Step 2

B Before Step 1

C Step 1

D After Step 2

💡 Hint

Look at the Condition and Branch Taken columns in the execution_table.

If x was 3 instead of 10, what would the output be?

A "Small"

B "Big"

C No output

D Error

💡 Hint

Refer to the key_moments explanation about condition false leading to else-block.

Concept Snapshot

if (condition) {
  // code if true
} else {
  // code if false
}

Checks condition once; runs if-block if true, else-block if false.

Full Transcript

This example shows how an if-else statement works in C++. The program starts by checking if x is greater than 5. Since x is 10, the condition is true, so it runs the code inside the if-block and prints "Big". If the condition were false, it would run the else-block and print "Small". The execution table shows each step: evaluating the condition, choosing the branch, and printing the output. The variable tracker shows that x stays 10 throughout. This helps beginners see how the program decides which code to run based on a condition.