Switch Statement in C

How to use switch case Statement in C?

Before using the switch case in our program, we need to know about some rules of the switch statement.

Rules of the switch case statement

Following are some of the rules that we need to follow while using the switch statement:

1. In a switch statement, the “ case value ” must be of “ char ” and “ int ” type.
2. There can be one or N number of cases.
3. The values in the case must be unique .
4. Each statement of the case can have a break statement. It is optional.
5. The default Statement is also optional.

Example

Case 1 is Matched.

How switch Statement Work?

The working of the switch statement in C is as follows:

1. Step 1: The switch variable is evaluated.
2. Step 2: The evaluated value is matched against all the present cases.
3. Step 3A: If the matching case value is found, the associated code is executed.
4. Step 3B: If the matching code is not found, then the default case is executed if present.
5. Step 4A: If the break keyword is present in the case, then program control breaks out of the switch statement.
6. Step 4B: If the break keyword is not present, then all the cases after the matching case are executed.
7. Step 5: Statements after the switch statement are executed.

We can also understand the working of the switch statement in C using the flowchart.

Flowchart of Switch Statement

Flowchart of switch statement in C

Break in switch case

This keyword is used to stop the execution inside a switch block. It helps to terminate the switch block and break out of it. When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement.

The break statement is optional . If omitted, execution will continue on into the next case. The flow of control will fall through to subsequent cases until a break is reached.

Example of switch case without break

Case 2 is executed. Case 3 is executed.Case 4 is executed.

Default in switch case

The default keyword is used to specify the set of statements to execute if there is no case match .

It is optional to use the default keyword in a switch case. Even if the switch case statement does not have a default statement, it would run without any problem.

Important Points About Switch Case Statements

1. Switch expression should result in a constant value

If the expression provided in the switch statement does not result in a constant value, it would not be valid. Some valid expressions for switch case will be,

// Constant expressions allowed switch(1+2+23) switch(1*2+3%4) // Variable expression are allowed provided // they are assigned with fixed values switch(a*b+c*d) switch(a+b+c) 

2. Expression value should be only of int or char type.

The switch statement can only evaluate the integer or character value. So the switch expression should return the values of type int or char only.

3. Case Values must be Unique

In the C switch statement, duplicate case values are not allowed.

3. Nesting of switch Statements

Nesting of switch statements is allowed , which means you can have switch statements inside another switch. However nested switch statements should be avoided as it makes the program more complex and less readable.

4. The default block can be placed anywhere

Regardless of its placement, the default case only gets executed if none of the other case conditions are met. So, putting it at the beginning, middle, or end doesn’t change the core logic.

Examples of switch Statement in C

Example 1: C Program to print the day of the week using a switch case.

The day with number 2 is Tuesday

Example 2: Simple Calculator using switch case in C

Output

Enter the operator (+, -, *, /) Enter x to exit + Enter the two numbers: 100 + 200 100 + 200 = 300

Advantages of C switch Statement

1. Easier to read than if else if.
2. Easier to debug and maintain for a large number of conditions.
3. Faster execution speed.

Disadvantages of C switch Statement

1. Switch case can only evaluate int or char type.
2. No support for logical expressions.
3. Have to keep in mind to add a break in every case.

Conclusion

In this article, we discussed the switch statement in C programming and how to use it. It is a conditional statement like the if-else-if ladder having its own merits and demerits. It is mostly preferred when the number of conditions to evaluate is large.

Switch Statement in C – FAQs

What is the switch case in C?

The switch case statement is a flow control statement in which we can define a switch variable and then execute different code based on the value of the switch variable. It is an alternative of if else if ladder.

What is the case in the switch statement in C?

The case keyword is used to define the different cases and their associated code in the switch statement.

What does the break in the switch case do?

The break keyword is used to exit the switch block after executing the matching case.

What are the differences between switch and if else if ladder in C?

• It executes the different cases on the basis of the value of the switch variable.
• It can only evaluate the int or char type expressions.
• Faster and easier to read for the large number of conditions.

• It executes the different blocks based on the condition specified.
• It can evaluate any type of expression.
• It can get messy when there are lots of conditions.

Must Read:

• Interesting Facts About Switch Case in C
• What should be Data type of Case Labels of Switch Statement in C?
• Print Individual Digits as Words Without Using if or Switch