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C switch…case

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What is a switch case in C?

In our earlier tutorials, we have studied about the If else statements, while, and do while loops. We have already learned how to use them in our programs to make it more efficient. In this tutorial, you will get to learn about the switch statement in C programming along with examples.  Switch case can works in the same fashion as the Else If Ladder statement. In Else If Ladder, the program will run the block which is true and thus in this way the program ends. Likewise, the switch statement is also a control statement which will select one of the many given choices. We will have values of expressions and a list which is built in reference to those values. The list thus created is known as a case. The program will execute that block of code which matches the case value. Generally, The Switch case is fast and have clear codes as compared to the Nested If Else statements. To demonstrate the concept more detailly, let’s go through the syntax of switch case:

Syntax:

switch(expression)
{
case value 1:
block 1;
break;
case value 2:
block 2;
break;
//You can use any number of case statements
default:
default statement;
break;
}
In the above syntax, we can see that the switch case executes in the same way as an Else if ladder statement. When the value in the expression matches any of the case values, then the block in that case executes. If all the values go unmatched then the default block executes and the program will end accordingly.  Now we will see the flowchart of the above statement that will help you to understand the concept more easily.

Flowchart:

As can be seen in the above flowchart, We will the program will check the expression at first. When the program runs, then all the cases will be checked. If Case value 1 is true, Block 1 will execute. Similarly, If Case value 2 is correct, then Block 2 executes. And finally, if none f the conditions are true then Default Block will execute.

Example:

Now let’s see how we can actually implement the switch case in our program. The program is very simple whose motive is to menu driven program. The feature of the program includes addition, subtraction, multiplication, division. Where the user will have a choice to perform the specific function.
Code:
#include<stdio.h>
int main(){
	int a,b;
	int n;
	printf("1. Addition\n");
	printf("2. Subtraction\n");
	printf("3. Multiplication\n");
	printf("4. DIvision\n");
	printf("Enter your choice (1 to 4): ");
	scanf("%d",&n);
	switch(n)
	{
		case 1:

			printf("Enter the value of a and b: ");
			scanf("%d%d",&a,&b);
			printf("Sum=%d",a+b);
			break;
		case 2:
			printf("Enter the value of a and b: ");
			scanf("%d%d",&a,&b);
			printf("Difference=%d",a-b);
			break;	
		case 3:
			printf("Enter the value of a and b: ");
			scanf("%d%d",&a,&b);
			printf("Multiplication=%d",(a*b));
			break;	
		case 4:
			printf("Enter the value of a and b: ");
			scanf("%d%d",&a,&b);
			printf("Division=%d",a/b);
			break;	
	default:	
	printf("Enter the number from 1 to 4.");
	}
}

The above code will provide the user with an option to jump into different blocks. When the user enters 1 then case 1 executes along with its block inside. Similarly, the program executes other cases on the basis of the number that user inputs to select the case number. And Finally, If the user enters a number that is not defined i.e. the number which is not in between 1 and 4 goes to the default block. Where default statements are executed. Below is an output of the code above.

Output:

  1. Addition
  2. Subtraction
  3.  Multiplication
  4.  Division

Enter your choice (1 to 4): 3
Enter the value of a and b: 3   4
Multiplication =12

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