How to Switch Statement in C

In C programming, the switch statement is a control statement that allows you to execute one of many code blocks based on the value of a variable or an expression. It provides a more readable and efficient way to handle multiple conditions compared to using multiple if-else statements.

Syntax of the Switch Statement:

switch (expression) {
    case constant1:
        // code to be executed if expression is equal to constant1
        break;
    case constant2:
        // code to be executed if expression is equal to constant2
        break;
    // More cases as needed
    default:
        // code to be executed if expression does not match any constant
}

• expression: The variable or expression whose value is being compared.
• case constant1, constant2, …: These are the values that the expression will be compared against. If the value of the expression matches a case constant, the corresponding block of code is executed.
• break: This statement terminates the switch block. Without it, the program continues executing the following cases (this is known as “fall-through”).
• default: An optional part of the switch block that is executed if none of the case labels match the value of the expression.

Example:

#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;
}

Explanation of the Example:

• The variable day is set to 3.
• The switch statement checks the value of day. Since day is 3, the code inside case 3 will execute, printing “Wednesday”.
• The break statement ensures that the program exits the switch block after executing the matching case.
• If the value of day did not match any case, the default case would execute and print “Invalid day”.

Advantages of Using Switch:

1. Simplifies Code: When you have many conditions based on the same variable or expression, switch makes the code easier to read and maintain.
2. Efficient: For certain compilers, switch may be more efficient than multiple if-else statements, especially when the conditions involve many possible values.

Important Points:

• Switch is used with integers, characters, or enumerated types: Most commonly, the switch expression is of type int or char. Some C compilers may also support enum types.
• Fall-through behavior: If a break statement is missing, execution will “fall through” to the next case statement, which might be useful in certain situations but can lead to bugs if unintended.
• Default case is optional: The default case is not required but is helpful for handling unexpected values.