C switch Statement

Posted in C Tutorial

Updated on Sep 06, 2024

By Mari Selvan

👁️ 52 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

The switch statement in C is a powerful control statement that allows you to execute different parts of code based on the value of an expression. It is an alternative to using multiple if-else statements and is particularly useful when you need to compare a variable to multiple possible values.

🤔 What is the switch Statement?

In C programming, the switch statement evaluates an expression and executes the corresponding case block based on the value of the expression. If no matching case is found, the default block is executed if it is present.

🔑 Key Features

Multi-way Branching: Simplifies the process of choosing between multiple actions.
Readability: Makes code easier to read compared to a long sequence of if-else statements.
Efficiency: Can be more efficient than if-else chains in terms of execution time.

💡 Syntax

The syntax for the switch statement is as follows:

example.c

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switch (expression) {
  case value1:
    // Statements
    break;
  case value2:
    // Statements
    break;
  // Additional cases...
  default:
    // Default statements
}

Explanation:

switch (expression): The expression is evaluated once and compared against the values of each case.
case value:: If the expression matches this value, the corresponding statements are executed.
break;: Exits the switch block. Without break, execution will fall through to the next case.
default: Optional: Executes if no case matches the expression.

Using the switch Statement:

Here’s a basic example of a switch statement:

example.c

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#include <stdio.h>

int main() {
  int day = 3;

  switch (day) {
    case 1:
      printf("Monday\n");
      break;
    case 2:
      printf("Tuesday\n");
      break;
    case 3:
      printf("Wednesday\n");
      break;
    case 4:
      printf("Thursday\n");
      break;
    case 5:
      printf("Friday\n");
      break;
    case 6:
      printf("Saturday\n");
      break;
    case 7:
      printf("Sunday\n");
      break;
    default:
      printf("Invalid day\n");
  }

    return 0;
}

💻 Output

In this example, if day is 3, the output will be:

Output

Wednesday

The default Case

The default case in a switch statement is executed if none of the case values match the expression. It is optional but recommended for handling unexpected values.

Example with default Case

example.c

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#include <stdio.h>

int main() {
  int grade = 'B';

  switch (grade) {
    case 'A':
      printf("Excellent!\n");
      break;
    case 'B':
      printf("Well done\n");
      break;
    case 'C':
      printf("Good\n");
      break;
    case 'D':
      printf("You passed\n");
      break;
    case 'F':
      printf("Better try again\n");
      break;
    default:
      printf("Invalid grade\n");
  }

  return 0;
}

💻 Output

If grade is 'B', the output will be:

Output

Well done

Fall-through Behavior

In C, if you omit the break statement, the program will continue executing the next case statements until it encounters a break or the end of the switch block. This is known as fall-through.

Example of Fall-through

example.c

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#include <stdio.h>

int main() {
  int number = 2;

  switch (number) {
    case 1:
      printf("One\n");
    case 2:
      printf("Two\n");
    case 3:
      printf("Three\n");
    default:
      printf("Default\n");
  }

  return 0;
}

💻 Output

The output will be:

Output

Two
Three
Default

📚 Common Pitfalls and Best Practices

Avoid Unintentional Fall-through:

Always use break unless intentional fall-through is required. Unintentional fall-through can lead to logical errors and unexpected behavior.
Use default Case:

Always include a default case to handle unexpected values, making your code more robust and easier to debug.
Limit Complex Logic:

Keep the logic within case blocks simple. If complex operations are required, consider calling functions instead to keep the switch statement readable.