Switch Case in C++

Switch case in C++ are control statements that can be used instead of if-else statements. The switch also helps us avoid the complex if-else ladder and makes the code easier to understand and modify for further use. This article explains the switch statement in C++ , uses, need, and implementation in the C++ language.

Syntax of Switch Statements in C++

Example

Output

Rules about Switch Case Statement in C++

1. The case value must be unique and can be an integer or a character.
2. Case names always end with a colon.
3. Default case labels are not required but can be up to one if defined.
4. Cases do not necessarily have to be in order 1, 2, 3, etc. You can enter in any order, depending on your requirements.
5. Identical Case values are not permitted.
6. Switch statements can also be nested.
7. A break statement is required to exit the switch case; otherwise, all cases following the matched case would be executed
8. Switch statement in C++ can be nested. On the other hand, Nested switch statements should be avoided because they make the program more complex and challenging to read.
9. The switch's expression must result in a constant value. Otherwise, the switch is invalid.

Example:

Constant expressions allowed

Variable expressions are permitted as long as they are given fixed values.

Flowchart of Switch Statement in C++

Explanation:

The value of the expression matches the values of the cases. If the value of the expression and the value of the case match, then the code corresponding to the respective case is executed, and after the whole code of that case is executed, then the break statement is executed. There can be any number of cases followed by a default keyword, which consists of the code to be executed when no case is matched to the value of the expression.

Working of Switch Case Statement in C++

The switch case statement in C++ operates by comparing the value of a variable or expression to a series of case labels within the switch block. Here's a step-by-step breakdown of its working mechanism:

1. Expression Evaluation: The switch statement evaluates the expression provided within its parentheses and compares it with case labels.
2. Case Matching: It compares the result with each case label, executing the code block of the matched case.
3. Code Execution: The associated code block is executed upon a match, followed by termination with a break statement.
4. Break Keyword: A break statement exits the switch, preventing the execution of subsequent cases.
5. Fall-through Behavior: Without break, execution continues to the next case, irrespective of a match.
6. Default Case: If no match is found, the code block under default is executed if provided.
7. End of Switch: Control proceeds to the statement following the switch block after executing a case or default block.

Important Points about Switch Case Statement in C++

1. Syntax: The syntax of a switch case in C++ is as follows:

2. Expression: The expression inside the switch parentheses is evaluated, and the value is compared with each case value.

3. Case Labels: Each case label specifies a constant value or an integer expression. If the value of the expression matches a case label, the corresponding code block is executed.

4. Break Statement: After executing the code block associated with a case label, the break statement exits the switch statement. Without a break, control will flow to the next case, potentially leading to unintended behaviour.

   Example Code without break keyword.

   Output:

   Output Explanation: In the code written above, no break keyword is used; hence, when the value of the expression matches the value of the corresponding case, the code starts executing and continues executing until the switch block's end. Therefore, all the Names after case 4 are printed.

5. Default Switch Case in C++: The default case is optional and is only executed if none of the case labels in the program match the value of the expression.

6. Fall-through: Unlike some other languages, C++ does not automatically exit the switch statement after executing a case block. If a break statement is omitted, control 'falls through' to the next case label, executing subsequent code blocks until a break is encountered

7. Optimization: Depending on the situation, the compiler may optimize the switch statement into more efficient code, such as using a jump table for consecutive integer case labels.

8. Usage: Switch case in C++ is commonly used when a variable or expression can take multiple distinct values, and different actions need to be performed based on those values. They provide a cleaner alternative to nested if-else statements in such scenarios.

Examples

Example 1: Using character as the value of the expression.

Let's learn the C++ switch case program:

Code:

Output:

Example 2:

An integer is used as the value of the expression.

Code:

Output:

Example 3:

When no case is matched to the given expression.

Code:

Output:

Example 4:

Using variables as the value of the expression.

Code:

Output:

Advantages of Switch Statement in C++

The most significant advantages of using the switch statement in C++ include:

1. The switch case in C++ is easier to read than the if-else statement.

2. This overcomes the challenges of the "if-else" ladder as that deepens the nesting and makes it difficult to compile. The switch statement helps you create a simple if-else ladder. The switch statement has a more precise and simpler syntax than the if-else ladder.

3. The depth of the switch statement is fixed. This allows for the most optimized implementation for faster code execution than the "if-else" ladder.

4. Debugging and maintaining your program using the switch statement in C++ is easy. The execution performance of the switch statement is fast.

5. If you need to compare the value of a variable with many other values, you need to use the switch statement. The break keyword prevents execution from proceeding to the next case. The default part of the option indicates that an action should be taken if there is no matching case.

Limitations

Switch Cas in C++ have some limitations, including:

1. No Range Checks: Unlike some languages, switch case C++ does not support ranges as case labels.

2. Fall-through Behavior: If a break statement is omitted after a case block, the control will "fall through" to the next case label. This behavior can lead to the unintended execution of multiple case blocks if not used carefully.

3. No Goto or Jump Labels: Switch case in C++ cannot be used with goto or jump labels. This means you cannot jump to a case label from outside the switch block or use goto to jump to another one within the switch block.

4. Limited String Support: Switch statement in C++ cannot be used directly with string variables or expressions.

5. Cannot Compare Non-Integral Types: The switch case cannot directly compare non-integral types. For example, you cannot use it with floating-point numbers or custom class objects.

6. No Complex Conditions: Switch case in C++ cannot handle complex conditions or expressions.