C++ Switch Case Control Structure

In this Tutorial we will understand and learn the working of C++ Switch Case Control Structure.
A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each case.
Switch case statements are a substitute for long if statements that compare a variable to several “integral” values (“integral” values are simply values that can be expressed as an integer, such as the value of a char).
The condition of a switch statement is a value.
An important thing to note about the switch statement is that the case values may only be constant integral expressions.
Switch case conditions cannot contain conditional statements (>, <, <=,>=). It can only contain a constant integral value (not even floating point values)

Flowchart of Switch Case

Flow Chart diagram of Switch Case Structure

Basic Syntax of Switch Case statement

switch(expression){
   case constant-expression  :
      statement(s);
      break; //optional
   case constant-expression  :
      statement(s);
      break; //optional
   // you can have any number of case statements.
   default : //Optional
      statement(s);
}

The following rules apply to a switch statement:

• The expression used in a switch statement must have an integral type.
• You can have any number of case statements within a switch. Each case is followed by the value to be compared to and a colon.
• The constant-expression for a case must be the same data type as the variable in the switch, and it must be a constant or a literal.
• When the variable being switched on is to a equal case, the statements following that case will execute until a break statement is reached.
• When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement.
• Not every case needs to contain a break. If no break appears, the flow of control will fall through to subsequent cases until a break is reached.
• A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.

Example program of Switch Case statement

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#include<iostream>
using namespace std;
int main()
{
	int num;
	cout<<"Enter a Number between 1 and 7:";
	cin>>num;
	
	switch(num)
	{
		case 1:
			cout<<"Monday";
			break;
		case 2:
			cout<<"Tuesday";
			break;
		case 3:
			cout<<"Wednesday";
			break;
		case 4:
			cout<<"Thursday";
			break;
		case 5:
			cout<<"Friday";
			break;
		case 6:
			cout<<"Saturday";
			break;
		case 7:
			cout<<"Sunday";
			break;
			
			// optional
		default:
			cout<<"Invalid Input";
	}
	// end of switch case

	return 0;
}

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