C switch

The switch statement is a control flow statement that allows you to select one of many possible code blocks to execute based on the value of an expression. It provides an alternative to using multiple if-else if statements when you need to make a decision among several options.

The basic syntax of the switch statement is as follows:

switch (expression) {
    case constant1:
        // Code to execute if expression equals constant1
        break; // Optional; used to exit the switch block

    case constant2:
        // Code to execute if expression equals constant2
        break;

    // Additional case labels as needed

    default:
        // Code to execute if expression does not match any case
}

Here’s how the switch statement works:

• The expression is evaluated, and its value is compared to the constants in the case labels.
• If a match is found, the code block associated with that case label is executed.
• The break statement is used to exit the switch block after executing the code for a matched case. If break is not used, execution will continue into subsequent case blocks until a break is encountered or the switch block ends.
• The default case is optional and is executed when none of the case labels match the value of the expression. It serves as the “default” action when no specific case is met.

Here’s an example that uses a switch statement to determine the day of the week based on a numeric value:

#include <stdio.h>

int main() {
    int day = 3; // Assuming 3 represents Wednesday

    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;
}

In this example, the value of day is compared to each case label, and the corresponding day of the week is printed. If day does not match any of the case labels, the default case is executed, indicating that it’s an invalid day.

A few key points to keep in mind when using switch:

• The expression inside the switch should evaluate to an integer or character type (e.g., int, char, enum).
• Each case label must be a constant expression (e.g., integer constants, character literals, or enumeration constants).
• Use break to exit the switch block when the desired case is found.
• The default case is optional but provides a fallback option for unmatched values.
• You can have multiple case labels for the same block of code (fall-through behavior) if multiple cases should execute the same code.

The switch statement is a powerful control flow construct for handling multiple conditional branches efficiently and is commonly used for menu-driven programs and state machines.