Switch Case in C

The switch statement in C is a control structure used to execute one block of code among many based on the value of an expression. It allows you to compare the value of a variable or expression against a series of constants and execute different blocks of code depending on which constant matches the value.

What is switch case in c ?

Syntax

switch (expression) { case constant1: // code to be executed if expression equals constant1 break; case constant2: // code to be executed if expression equals constant2 break; // you can have any number of case statements default: // code to be executed if expression doesn't match any case }

Key Points

expression : The variable or expression whose value is compared against the case constants.
case constant : A constant value that the expression is compared to.
break : Exits the switch statement. If omitted, execution will continue to the next case (fall-through).
default : Optional. Executes if no case matches the expression.

Examples

C Code

#include <stdio.h>

main() {
    int day = 3;

    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");
            break;
    }
}

Explanation :
- The variable day is set to 3.
- The switch statement compares day to each case.
- When day is 3, the code in case 3: executes, printing "Wednesday".
- The break statement prevents the execution from falling through to the next cases.
- If day were not between 1 and 7, the default case would execute, printing "Invalid day".

Problems & Solutions

Write a Program to accept a month and display the number of days present in that

#include<stdio.h>
int main()
{
	int ch;
	printf("1.Jan\n");
	printf("2.Feb\n");
	printf("3.Mar\n");
	printf("4.Apr\n");
	printf("5.May\n");
	printf("6.Jun\n");
	printf("7.Jul\n");
	printf("8.Aug\n");
	printf("9.sep\n");
	printf("10.oct\n");
	printf("11.Nov\n");
	printf("12.dec\n");
	printf("Enter month no :");
	scanf("%d",&ch);
	switch(ch)
	{
		case 1:
			printf("31 days");
			break;
		case 2:
			printf("28 days");
			break;
		case 3:
			printf("31 days");
			break;
		case 4:
			printf("30 days");
			break;
		case 5:
			printf("31 days");
			break;
		case 6:
			printf("30 days");
			break;
		case 7:
			printf("31 days");
			break;
		case 8:
			printf("31 days");
			break;
		case 9:
			printf("30 days");
			break;
		case 10:
			printf("31 days");
			break;
		case 11:
			printf("30 days");
			break;
		case 12:
			printf("31 days");
			break;
			default:
				printf("Invalid choice");
				break;
			
	}
}

Output
Enter month no :5
31 days

Using switch case statement, write a menu driven program to convert a given temp

#include<stdio.h>
main()
{
	int n,c,a;
	float f;
	printf("1.fah to cel\n");
	printf("2.cel to fah\n");
	printf("enter choice:");
	scanf("%d",&n);
	switch(n)
	{
		case 1:
			printf("enter fah val:");
			scanf("%d",&a);
			c=(a-32)/5*9;
			printf("%d",c);
		break;
		case 2:
			printf("enter cel val:");
			scanf("%d",&a);
			f=1.8*a+32;
			printf("%f",f);
		break;
		default:
			printf("invalid choice");
		    break;	
			
	}
	
}

Output
1.fah to cel
2.cel to fah
enter choice:1
enter fah val:200
297

Write a program to display the colour of the spectrum (VIBGYOR) according to the

#include<stdio.h>
main()
{
	int ch;
	printf("VIBGYOR\n");
	printf("Enter colour : ");
	scanf("%c",&ch);
	switch(ch)
	{
		case 'V':
			printf("violet");
			break;
		case 'I':
		    printf("indigo");
			break;
		case 'B':
		    printf("blue");
			break;
		case 'G':
		    printf("green");
			break;
		case 'Y':
		    printf("yellow");
			break;
		case 'O':
		    printf("orange");
			break;
		case 'R':
		    printf("red");
			break;
		default:
		printf("invalid choice");
		break;							
	}
}

Output
VIBGYOR
Enter colour : R
red

Conclusion

The switch statement in C is a powerful control structure that enhances code readability, maintainability, and efficiency. It is particularly useful when dealing with a variable that can take on multiple discrete values. By centralizing all related conditions, it provides a clear and organized way to handle complex branching logic.