Switch statement in C++ - Step-by-Step Execution

Concept Flow - Switch statement

Start

↓

Evaluate expression

↓

Match case?

No→Default case?

↓

Execute case

↓

Break?

No→Continue to next case

Yes↓

Exit switch

The switch statement evaluates an expression, matches it to a case, executes that case's code, and exits or continues based on break statements.

Execution Sample

C++

#include <iostream>
using namespace std;

int day = 3;
switch(day) {
  case 1: cout << "Monday"; break;
  case 2: cout << "Tuesday"; break;
  case 3: cout << "Wednesday"; break;
  default: cout << "Invalid day";
}

This code prints the name of the day based on the integer value of 'day'.

Execution Table

Step	Expression Value	Case Checked	Match?	Action	Output
1	3	case 1	No	Skip
2	3	case 2	No	Skip
3	3	case 3	Yes	Execute and break	Wednesday
4	-	-	-	Exit switch

💡 Break after case 3 causes exit from switch.

Variable Tracker

Variable	Start	After switch
day	3	3

Key Moments - 3 Insights

Why does the switch stop after printing "Wednesday"?

Because the 'break' statement after case 3 stops further case checks and exits the switch (see execution_table step 3).

What happens if there is no 'break' after a case?

Execution continues to the next case's code until a break or the switch ends, causing multiple outputs (not shown here but important).

When is the 'default' case executed?

Only if no case matches the expression value, then the default code runs (not triggered in this example).

Visual Quiz - 3 Questions

Look at the execution table, which case matches the expression value?

A case 3

B case 2

C case 1

D default

💡 Hint

Check the 'Match?' column in the execution_table rows.

At which step does the switch statement exit?

A Step 2

B Step 4

C Step 3

D After default case

💡 Hint

Look at the 'Action' column for when 'Exit switch' happens.

If the 'break' after case 3 was removed, what would happen?

A Only case 3 executes

B Switch exits immediately

C Execution continues to default case

D Compilation error

💡 Hint

Recall that without break, execution falls through to next cases.

Concept Snapshot

switch(expression) {
  case value1: 
    // code
    break;
  case value2:
    // code
    break;
  default:
    // code
}

- Evaluates expression once
- Matches cases in order
- Executes matched case
- 'break' exits switch
- 'default' runs if no match

Full Transcript

A switch statement evaluates an expression and compares it to multiple cases. It runs the code for the matching case and stops if it finds a break statement. If no case matches, it runs the default case if present. In the example, the variable 'day' is 3, so the switch matches case 3 and prints 'Wednesday'. The break after case 3 stops the switch from running other cases. Without break, the switch would continue running the next cases until it finds a break or ends. This helps choose between many options clearly and efficiently.