C++ Do While Repetition Statement
The do while in C++
The do…while repetition statement is similar to the while statement. In the while statement, the loop-continuation condition test occurs at the beginning of the loop before the body of the loop executes.
The do…while statement tests the loop-continuation condition after the loop body executes; therefore, the loop body always executes at least once.C++ is also popular because of its portability.
The following code demonstrates the do while statement:
do
{
statement
} while ( condition );
When a do…while terminates, execution continues with the statement after the while clause.
It’s not necessary to use braces in the do while statement if there’s only one statement in the body; however, most programmers include the braces to avoid confusion between the while and do…while statements.
Do while statement to print the numbers 1–10.
#include <iostream>
using namespace std;
int main()
{
int counter = 1; // initialize counter
do
{
cout << counter << " "; // display counter
++counter; // increment counter
} while ( counter <= 10 ); // end do...while
cout << endl; // output a newline
} // end main
Output:
1 2 3 4 5 6 7 8 9 10
Using do while with Switch Case menus
The do-while loop is a good choice for repeating a menu. This program, displays a menu of health club packages.
The menu-driven Health Club membership program carries out the appropriate actions based on the menu choice entered. A do-while loop allows the program to repeat until the user selects menu choice 4.
#include <iostream.h>
#include <iomanip.h>
using namespace std;
int main()
{
const double ADULT_RATE = 40.0;
const double CHILD_RATE = 20.0;
const double SENIOR_RATE = 30.0;
int choice; // Menu choice
int months; // Number of months
double charges; // Monthly charges
do
{
// Display the menu and get the user's choice
cout << "\n Health Club Membership Menu\n\n";
cout << "1. Standard Adult Membership\n";
cout << "2. Child Membership\n";
cout << "3. Senior Citizen Membership\n";
cout << "4. Quit the Program\n\n";
cout << "Enter your choice: ";
cin >> choice;
// Validate the menu selection
while ((choice < 1) || (choice > 4))
{
cout << "Please enter 1, 2, 3, or 4: ";
cin >> choice;
}
// Process the user's choice
if (choice != 4)
{ cout << "For how many months? ";
cin >> months;
// Compute charges based on user input
switch (choice)
{
case 1: charges = months * ADULT_RATE;
break;
case 2: charges = months * CHILD_RATE;
break;
case 3: charges = months * SENIOR_RATE;
}
// Display the monthly charges
cout << fixed << showpoint << setprecision(2);
cout << "The total charges are $" << charges << endl;
}
} while (choice != 4); // Loop again if the user did not
// select choice 4 to quit
return 0;
}
Output with Example Input Shown in Bold:
Health Club Membership Menu
1. Standard Adult Membership
2. Child Membership
3. Senior Citizen Membership
4. Quit the Program
Enter your choice: 1
For how many months? 12
The total charges are $480.00
Health Club Membership Menu
1. Standard Adult Membership
2. Child Membership
3. Senior Citizen Membership
4. Quit the Program
Enter your choice: 4
Ads Right
