Case Keyword

In C programming, the case keyword is a fundamental component of the switch statement, providing a powerful mechanism for multi-way branching and control flow.

Case Keyword

The case keyword allows you to specify different cases or values to be matched against a given expression, determining the flow of execution within the switch statement.

The switch statement evaluates the expression once and compares it to the values specified in each case.

When a match is found, the corresponding block of code is executed, and execution continues until a break statement is encountered, or the switch statement ends.

Here's an example of using the case keyword within a switch statement:

int num = 2;
switch (num) {
  case 1:
    // Code to be executed if num is 1
    break;
  case 2:
    // Code to be executed if num is 2
    break;
  default:
    // Code to be executed if num does not match any case
    break;
}

In this example, the switch statement evaluates the value of the variable num. If num is 1, the code within the first case block is executed.

If num is 2, the code within the second case block is executed. If num does not match any of the specified cases, the code within the default block is executed.

The break statements ensure that execution exits the switch statement after each case is handled.

It's important to note that cases within a switch statement must be unique and cannot overlap.

Additionally, the switch statement can have an optional default case, which is executed when none of the cases match the evaluated expression.

  • The case keyword provides a concise and efficient way to handle multiple possibilities and control flow within a switch statement.

  • Proper usage of the case keyword allows for clear and organized code that effectively handles different scenarios.

The Importance of the break Statement

In C, it's essential to use the break statement after each case.

If the break is omitted, and a case matches, the program will execute all subsequent case blocks until it encounters a break or reaches the end of the switch statement, a behavior known as "fall-through."

switc(expression){
    case 0://without break
    case 1: //without break
    case 2:
    break;
    default:
    break;
}

The default Case

The default case is optional and can be used for handling unexpected values.

It doesn't require a break statement since it's always the last case.

Practical Example

#include <stdio.h>
int main() {
    int day = 5;
    
    switch(day) {
        case 1:
            printf("Monday");
            break;
        case 2:
            printf("Tuesday");
            break;
        case 3:
            printf("Wednesday");
            break;
        case 4:
            printf("Thursday");
            break;
        case 5:
            printf("Friday");
            break;
        case 6:
            printf("Saturday");
            break;
        case 7:
            printf("Sunday");
            break;
        default:
            printf("Invalid day");
    }
    
    return 0;
}

In the above code, the program will print "Friday" since the value of day is 5.

Limitations

  • The switch statement can only evaluate integer and character data types.
  • Floating-point numbers and strings cannot be used directly.
  • Each case must be unique; duplicate values are not allowed.
  • The case values must be constant. Variables or expressions that result in variable values are not permitted.

The case keyword, when used within the switch statement, offers an efficient way to handle multi-way decisions in C. While it's a powerful tool, programmers should use it judiciously, ensuring that the code remains readable and maintainable.

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