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If-else statements are like the Swiss Army knife of decision-making. They offer flexibility and can handle a wide range of conditions and branching logic. You can use them when you need to evaluate complex conditions or when conditions aren’t based on simple equality checks. If-else statements are often the preferred choice for scenarios where the conditions are not easily enumerable or where you need to execute different blocks of code based on various conditions.
On the other hand, switch statements shine when you have a single variable to compare against multiple distinct values. They are concise, making the code cleaner and more structured. So, if-else statements and switch statements can complement each other, with if-else statements handling complex conditions and switch statements simplifying cases with multiple exact matches.
The ‘Switch’ Statement
To illustrate the switch statement, let’s consider a common problem: given a number between 1 and 7, print the corresponding day of the week. Here’s how we can use the switch statement for this task:
Code:
C++ Code
#include <iostream>
using namespace std;
int main() {
int day = 4;
switch (day) {
case 1:
cout << "Monday";
break;
case 2:
cout << "Tuesday";
break;
case 3:
cout << "Wednesday";
break;
case 4:
cout << "Thursday";
break;
case 5:
cout << "Friday";
break;
case 6:
cout << "Saturday";
break;
case 7:
cout << "Sunday";
break;
default:
cout << "Invalid";
}
return 0;
}
Output: Thursday
Java Code
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
int day;
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number (1-7): ");
day = scanner.nextInt();
switch (day) {
case 1:
System.out.println("Monday");
break;
case 2:
System.out.println("Tuesday");
break;
case 3:
System.out.println("Wednesday");
break;
case 4:
System.out.println("Thursday");
break;
case 5:
System.out.println("Friday");
break;
case 6:
System.out.println("Saturday");
break;
case 7:
System.out.println("Sunday");
break;
default:
System.out.println("Invalid");
}
scanner.close();
}
}
Output: Thursday
In this example, if you set the day variable to 4, it will print “Thursday” since it matches the case 4 statement. The break statement is crucial; it ensures that the switch statement exits after the matching case is executed, preventing the execution of subsequent cases.
The Default Case: The default case serves as a safety net. If none of the cases match the expression, the code inside the default block will execute. In our example, if you input a number outside the range of 1 to 7, it will print “Invalid.”
Key Considerations for Switch Case Statements:
- Requirement for a Constant Expression
A switch statement necessitates that its expression results in a constant value. This can include constants and arithmetic operations.
Code:
C++ Code
#include <iostream>
using namespace std;
int main() {
const int x = 10;
const int y = 5;
switch (x + y) {
case 15:
cout << "Result is 15." << endl;
break;
case 20:
cout << "Result is 20." << endl;
break;
default:
cout << "No match found." << endl;
}
return 0;
}
Output: Result is 15.
Java Code
public class Main {
public static void main(String[] args) {
final int x = 10;
final int y = 5;
switch (x + y) {
case 15:
System.out.println("Result is 15.");
break;
case 20:
System.out.println("Result is 20.");
break;
default:
System.out.println("No match found.");
}
}
}
Output: Result is 15.
- Limited to Integer or Character Types
Switch statements are exclusively designed to handle integer or character values. Ensure that the expression provides values of type int or char.
Code:
C++ Code
#include <iostream>
using namespace std;
int main() {
char grade = 'B';
switch (grade) {
case 'A':
cout << "Excellent!" << endl;
break;
case 'B':
cout << "Good!" << endl;
break;
default:
cout << "Not specified." << endl;
}
return 0;
}
Output: Good!
Java Code
public class Main {
public static void main(String[] args) {
char grade = 'B';
switch (grade) {
case 'A':
System.out.println("Excellent!");
break;
case 'B':
System.out.println("Good!");
break;
default:
System.out.println("Not specified.");
}
}
}
Output: Good!
- Significance of the ‘Break’ Keyword
The ‘break’ keyword holds significant importance within switch cases. It serves as an exit mechanism from the switch statement. Its omission implies the execution of all subsequent cases. - Optional Default Case
Optionally, you can include a ‘default’ case, which executes when none of the case values match. It’s not obligatory and can be excluded if not needed.
- Prohibition of Duplicate Case Values
Within a switch statement in C++, duplicates of case values are disallowed. Each case value must be distinct.
Code:
C++ Code
#include <iostream>
using namespace std;
int main() {
int day = 2;
switch (day) {
case 1:
cout << "Monday." << endl;
break;
case 2:
cout << "Tuesday." << endl;
break;
case 2: // Duplicate case, not allowed
cout << "Duplicate case." << endl;
break;
default:
cout << "Invalid day." << endl;
}
return 0;
}
Java Code
public class Main {
public static void main(String[] args) {
int day = 2;
switch (day) {
case 1:
System.out.println("Monday.");
break;
case 2:
System.out.println("Tuesday.");
break;
case 2: // This line will result in a compilation error in Java
System.out.println("Duplicate case.");
break;
default:
System.out.println("Invalid day.");
}
}
}
- Potential for Nested Switch Statements
While it’s possible to nest one switch statement inside another in C++, this practice is generally discouraged due to its potential to introduce complexity and hinder code readability.
Code:
C++ Code
#include <iostream>
using namespace std;
int main() {
int x = 2;
int y = 3;
switch (x) {
case 1:
cout << "x is 1." << endl;
switch (y) {
case 1:
cout << "y is 1." << endl;
break;
default:
cout << "y is not 1." << endl;
}
break;
default:
cout << "x is not 1." << endl;
}
return 0;
}
Java Code
public class Main {
public static void main(String[] args) {
int x = 2;
int y = 3;
switch (x) {
case 1:
System.out.println("x is 1.");
switch (y) {
case 1:
System.out.println("y is 1.");
break;
default:
System.out.println("y is not 1.");
}
break;
default:
System.out.println("x is not 1.");
}
}
}
Special thanks to Gauri Tomar for contributing to this article on takeUforward. If you also wish to share your knowledge with the takeUforward fam, please check out this article