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The switch statement in C++ is a control structure that allows you to execute one of many code blocks based on the value of an expression. It’s often used as an alternative to multiple if-else statements, making the code more readable and efficient when checking a variable against multiple possible values.
Basic Syntax of the switch Statement
switch (expression) {
case constant1:
// Code to execute if expression == constant1
break;
case constant2:
// Code to execute if expression == constant2
break;
...
default:
// Code to execute if no cases match
}
- Expression: The value that is compared against each case. It must be of an integral or enumeration type (such as int, char).
- Case labels: Each case defines a possible value for the expression and the corresponding code to execute.
- Break statement: Ends each case. Without break, execution continues to the next case (known as fall-through).
- Default case: Executes if none of the cases match the expression. It’s optional but recommended.
1. Basic switch Statement Example
A simple switch statement that prints a message based on the value of a char variable.
#include <iostream>
using namespace std;
int main() {
char grade = 'B';
switch (grade) {
case 'A':
cout << "Excellent!" << endl;
break;
case 'B':
cout << "Good job!" << endl;
break;
case 'C':
cout << "Well done!" << endl;
break;
default:
cout << "Invalid grade." << endl;
}
return 0;
}
Explanation:
- The switch statement compares grade against each case. If grade is ‘B', it prints “Good job!” and breaks out of the switch.
Output:
Good job!
2. switch Statement with Integer Cases
A switch statement that checks an integer value and performs an action based on its value.
#include <iostream>
using namespace std;
int main() {
int day = 3;
switch (day) {
case 1:
cout << "Monday" << endl;
break;
case 2:
cout << "Tuesday" << endl;
break;
case 3:
cout << "Wednesday" << endl;
break;
case 4:
cout << "Thursday" << endl;
break;
case 5:
cout << "Friday" << endl;
break;
default:
cout << "Weekend!" << endl;
}
return 0;
}
Explanation:
- Each case corresponds to a day of the week. If day is 3, it prints “Wednesday.”
Output:
Wednesday
3. switch Statement with default Case
The default case is executed if none of the cases match the expression.
#include <iostream>
using namespace std;
int main() {
int option = 5;
switch (option) {
case 1:
cout << "Option 1 selected." << endl;
break;
case 2:
cout << "Option 2 selected." << endl;
break;
default:
cout << "Invalid option." << endl;
}
return 0;
}
Explanation:
- Since option is 5, which doesn’t match any case, the default case is executed, printing “Invalid option.”
Output:
Invalid option.
4. switch Statement with Multiple Statements in a Case
A case in a switch statement can contain multiple lines of code.
#include <iostream>
using namespace std;
int main() {
int choice = 1;
switch (choice) {
case 1:
cout << "Choice 1 selected." << endl;
cout << "You have selected option 1." << endl;
break;
case 2:
cout << "Choice 2 selected." << endl;
cout << "You have selected option 2." << endl;
break;
default:
cout << "Invalid choice." << endl;
}
return 0;
}
Explanation:
- When choice is 1, both statements under case 1 are executed.
Output:
Choice 1 selected. You have selected option 1.
5. switch Statement with Fall-Through Behavior
If you omit the break statement, the switch statement will continue executing the next cases until a break or the end of the switch.
#include <iostream>
using namespace std;
int main() {
int number = 2;
switch (number) {
case 1:
cout << "One" << endl;
case 2:
cout << "Two" << endl;
case 3:
cout << "Three" << endl;
default:
cout << "Default case" << endl;
}
return 0;
}
Explanation:
- Because there’s no break after case 2, execution “falls through” to case 3 and default.
Output:
Two Three Default case
6. Grouping Cases
You can group multiple cases together if they perform the same action.
#include <iostream>
using namespace std;
int main() {
char letter = 'A';
switch (letter) {
case 'A':
case 'E':
case 'I':
case 'O':
case 'U':
cout << "The letter is a vowel." << endl;
break;
default:
cout << "The letter is a consonant." << endl;
}
return 0;
}
Explanation:
- If letter is any of the vowels (‘A', ‘E', ‘I', ‘O', ‘U'), it prints “The letter is a vowel.”
Output:
The letter is a vowel.
7. switch Statement with User Input
You can use a switch statement to respond to user input.
#include <iostream>
using namespace std;
int main() {
int choice;
cout << "Enter 1, 2, or 3: ";
cin >> choice;
switch (choice) {
case 1:
cout << "You selected option 1." << endl;
break;
case 2:
cout << "You selected option 2." << endl;
break;
case 3:
cout << "You selected option 3." << endl;
break;
default:
cout << "Invalid choice." << endl;
}
return 0;
}
Explanation:
- The user’s input determines which case executes. If the input isn’t 1, 2, or 3, it defaults to “Invalid choice.”
Sample Output:
Enter 1, 2, or 3: 2 You selected option 2.
8. Using switch to Evaluate an Enumeration
Enumerations (enums) can be used in a switch statement, as they are integral types.
#include <iostream>
using namespace std;
enum Direction { NORTH, SOUTH, EAST, WEST };
int main() {
Direction dir = SOUTH;
switch (dir) {
case NORTH:
cout << "Heading North" << endl;
break;
case SOUTH:
cout << "Heading South" << endl;
break;
case EAST:
cout << "Heading East" << endl;
break;
case WEST:
cout << "Heading West" << endl;
break;
}
return 0;
}
Explanation:
- dir is an enum of type Direction. switch compares it to each Direction case.
Output:
Heading South
9. Using switch for Simple Calculations
The switch statement can handle simple calculations based on user input.
#include <iostream>
using namespace std;
int main() {
char op;
double num1, num2;
cout << "Enter an operator (+, -, *, /): ";
cin >> op;
cout << "Enter two numbers: ";
cin >> num1 >> num2;
switch (op) {
case '+':
cout << "Result: " << num1 + num2 << endl;
break;
case '-':
cout << "Result: " << num1 - num2 << endl;
break;
case '*':
cout << "Result: " << num1 * num2 << endl;
break;
case '/':
if (num2 != 0)
cout << "Result: " << num1 / num2 << endl;
else
cout << "Cannot divide by zero." << endl;
break;
default:
cout << "Invalid operator." << endl;
}
return 0;
}
Explanation:
- The user inputs an operator and two numbers, and the switch performs the operation.
- The default case handles invalid operators, and a conditional check prevents division by zero.
Sample Output:
Enter an operator (+, -, *, /): * Enter two numbers: 4 5 Result: 20
10. Summary Table
| Use Case | Code Example | Description |
|---|---|---|
| Basic switch statement | switch(x) { case … } | Executes code based on x |
| Integer cases | case 1: … case 2: … | Matches integer values |
| Default case | default: … | Runs if no case matches |
| Multiple statements | case 1: …; …; break; | Multiple lines in one case |
| Fall-through | Omit break | Executes subsequent cases |
| Grouping cases | case ‘A': case ‘E': | Groups cases with same action |
| User input switch | switch(userInput) {…} | Responds to user input |
| Enum with switch | switch(enumValue) {…} | Compares enum values |
| Simple calculations | switch(operator) {…} | Switch based on operation |
Complete Example: Switch Statement with Multiple Uses
This example demonstrates a switch statement handling different cases, including user input, fall-through behavior, and a default case.
#include <iostream>
using namespace std;
int main() {
int menuOption;
cout << "Select an option (1, 2, or 3): ";
cin >> menuOption;
switch (menuOption) {
case 1:
cout << "Option 1: View Account" << endl;
break;
case 2:
cout << "Option 2: Deposit Money" << endl;
cout << "Deposit feature is selected." << endl;
break;
case 3:
cout << "Option 3: Withdraw Money" << endl;
break;
default:
cout << "Invalid option selected." << endl;
}
return 0;
}
Explanation:
- The user selects a menu option, and the switch statement directs them to the appropriate action.
- If the option is not 1, 2, or 3, it falls to the default case.
Sample Output:
Select an option (1, 2, or 3): 2 Option 2: Deposit Money Deposit feature is selected.
The switch statement in C++ provides an efficient and clean way to handle multiple conditions, especially when dealing with multiple fixed values.