Switch Case Example in C with Menu-Driven Program

Introduction

The switch statement in the C programming language is a powerful decision-making tool that simplifies the handling of multiple conditions. This is quite useful when you are required to compare a single variable against a multiple set of values.

Not like a lengthy if-else statement, this switch statement in C provides a clean and organised way to execute specific code blocks based on the value of a variable.

From creating this menu-driven program to processing inputs switch statement is just a common and most used tool in programming. So let's learn how this switch statement works, syntax, and also switch use cases in C with simple programming examples.

What is Switch Case in C?

This case is a switch statement in C programming that acts like a control structure used mostly to execute one block of code. One can do this with multiple options, just based on the value of the expression. The Expression's value is compared against a predefined constant set of cases, and the matching block is executed.

If one finds no match, then in such a case default block, if by chance provided, will be executed to get a particular output. Your input. Each button just corresponds to a different set of outputs.

Syntax of Switch Statement in C

Below is the syntax of the switch statement in the C programming language

Program code:

switch (expression) {

case constant1:

// Code to execute if expression matches constant1

break;

case constant2:

// Code to execute if expression matches constant2

break;

...

Default:

// Code to execute if no case matches

}

Component Explanation :

Component

Explanation

switch (expression)

So this expression is evaluated just once and later compared against constants in each of the cases. It must simply result in an integer or character value.

case constant

Just represents a specific value to compare with the expression. Each of the case labels needs to have a unique constant value.

Statements

This is simply code to execute when the case meets the expression. This often can include multiple lines of code.

break

Will end the execution of the current ongoing process and exit the switch block. Without applying a break program will continue to execute subsequent stages. We also call it a fall-through behaviour.

default

One of the options blocks is often executed when no case matches the expression. It simply acts as a catch for all unmatched expressions.

Some of the practical examples to understand the switch case statement

Program code :

#include

int main() {

int day;

printf("Enter a number (1-7): ");

scanf("%d", &day);

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.:

Input: 3 → Output: Wednesday

Input: 8 → Output: Invalid day

Explanation of the above example

• Expression - This is the day when the variable is evaluated in the switch statement.

• Case Matching - If input is 3, then it will match case 3 and also print "Wednesday".

• Break - Will stop execution of matching case to prevent any kind of fall-through.

• Default - If the input is not between 1 and 7, then the default block will print "invalid day".

How Switch Case in C Works?

Below is by step-by-step guide on how switch case in C works :

1. Evaluate the Expression required - Firstly expression inside the switch statement is evaluated first. It must simply result in an integer or character value.

2. Compare with Case Constants - The program will just compare the value of a particular expression with each of the case constants in the switch block. If this match is found, then the program will execute the code under that case.

3. Execute Matching Case - Whenever a match is found, then the code under that corresponding case will be executed until a break statement is encountered or even end of the switch statement block is reached.

4. Break Statement - This break statement in C will end execution of the current ongoing process and exit the switch block. Without a break program will simply continue to execute subsequent cases.

5. Default Case - If no case matches the execution, then the default optional block will be executed. If by chance the default block is not present, then the program will skip the switch block entirely.

6. Continue Program Execution - After executing this matching case or even the default case, the program will move to the next statement outside the switch block.

C Switch Case Examples

Below are some of the common examples of a switch in C programming :

1. Perform Basic Arithmetic Operations

Program code :

#include

int main() {

int num1, num2, result;

char operator;

printf("Enter two numbers: ");

scanf("%d %d", &num1, &num2);

printf("Enter an operator (+, -, *, /): ");

scanf(" %c", &operator);

switch (operator) {

case '+':

result = num1 + num2;

printf("Result: %d\n", result);

break;

Case '-':

result = num1 - num2;

printf("Result: %d\n", result);

break;

case '*':

result = num1 * num2;

printf("Result: %d\n", result);

break;

Case '/':

if (num2!= 0) {

result = num1 / num2;

printf("Result: %d\n", result);

}

break;

default:

printf("Invalid operator\n");

}

return 0;

}

Output :

Enter two numbers: 5 10

Enter an operator (+, -, *, /): +

Result: 15

2. Check Vowel Consonant

Program code :

#include

int main() {

char ch;

printf("Enter a character: ");

scanf(" %c", &ch);

switch (ch) {

case 'a': case 'e': case 'i': case 'o': case 'u':

case 'A': case 'E': case 'I': case 'O: case 'U':

printf("The character is a vowel.\n");

break;

Default:

printf("The character is a consonant.\n");

}

return 0;

}

Output :

Enter a character: u

The character is a vowel.

3. Simple Calculator Menu

Program code :

#include

int main() {

int choice, a, b;

printf("Menu:\n");

printf("1. Add\n2. Subtract\n3. Multiply\n4. Divide\n");

printf("Enter your choice: ");

scanf("%d", &choice);

printf("Enter two numbers: ");

scanf("%d %d", &a, &b);

switch (choice) {

Case 1:

printf("Sum: %d\n", a + b);

break;

Case 2:

printf("Difference: %d\n", a - b);

break;

Case 3:

printf("Product: %d\n", a * b);

break;

Case 4:

if (b!= 0) {

printf("Quotient: %d\n", a / b);

}

break;

default:

printf("Invalid choice\n");

}

return 0;

}

Output :

Menu:

1. Add
2. Subtract
3. Multiply
4. Divide

Enter your choice: 1

Enter two numbers: 92929 48

Sum: 92977

4. Check Student Grade

Program code :

#include

int main() {

int marks;

printf("Enter your marks: ");

scanf("%d", &marks);

switch (marks / 10) { // Integer division to group marks

case 10: case 9:

printf("Grade: A\n");

break;

Case 8:

printf("Grade: B\n");

break;

Case 7:

printf("Grade: C\n");

break;

Case 6:

printf("Grade: D\n");

break;

Default:

printf("Grade: F\n");

}

return 0;

}

Output :

Enter your marks: 6

Grade: F

5. Determine the Type of Triangle

Program code :

#include

int main() {

int a, b, c;

printf("Enter three sides of the triangle: ");

scanf("%d %d %d", &a, &b, &c);

switch ((a == b) + (b == c) + (c == a)) {

Case 3:

printf("The triangle is equilateral.\n");

break;

Case 1:

printf("The triangle is isosceles.\n");

break;

Default:

printf("The triangle is scalene.\n");

}

return 0;

}

Output:

Enter three sides of the triangle: 4 5, 3

The triangle is scalene.

Nested Switch Statement in C

A nested switch statement just refers to one switch statement inside another switch statement. This often allows for handling complex decision-making scenarios. Here, frequently, one condition depends on the result of another. The outer switch statement will evaluate the expression first, and based on the matching case inner switch will execute the code block.

Real-Life Example:

• Outer decision ( Outer Switch ) - Choose the type of meal first ( like vegetarian or non-vegetarian ).

• Inner Decision (Inner Switch) - Based on this meal type, one can choose specific dishes ( vegetarian → paneer or dal, non-vegetarian → chicken or fish)

Syntax for this kind of nested switch statement :

switch (expression1) {

case constant1:

// Code for constant1

switch (expression2) {

case constant2_1:

// Code for constant2_1

break;

case constant2_2:

// Code for constant2_2

break;

Default:

// Default code for inner switch

}

break;

case constant2:

// Code for constant2

break;

Default:

// Default code for outer switch

}

Example of nested switch in the C programming language

Meal selection based on type as well as dish

Program code :

#include

int main() {

int mealType, dish;

printf("Select meal type (1 for Vegetarian, 2 for Non-Vegetarian): ");

scanf("%d", &mealType);

switch (mealType) {

case 1: // Vegetarian

printf("Select dish (1 for Paneer, 2 for Dal): ");

scanf("%d", &dish);

switch (dish) {

Case 1:

printf("You selected Paneer.\n");

break;

Case 2:

printf("You selected Dal.\n");

break;

Default:

printf("Invalid dish selection for Vegetarian meal.\n");

}

break;

case 2: // Non-Vegetarian

printf("Select dish (1 for Chicken, 2 for Fish): ");

scanf("%d", &dish);

switch (dish) {

Case 1:

printf("You selected Chicken.\n");

break;

Case 2:

printf("You selected Fish.\n");

break;

Default:

printf("Invalid dish selection for Non-Vegetarian meal.\n");

}

break;

Default:

printf("Invalid meal type.\n");

}

return 0;

}

Output :

Select meal type (1 for Vegetarian, 2 for Non-Vegetarian): 1

Select dish (1 for Paneer, 2 for Dal): 1

You selected Paneer.

Conclusion :

Switch cases are quite essential for learning, as they are useful in many cases. So, enrolling in a C programming course in Noida will be of great help for you and stay relevant as per industry demands.

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