What is the point of do{} while()?

Question

Surely all conditional statements should output only if the while statement is true. If the "do" always outputs once without any condition, what is its purpose? Can someone give a usage example please?

Answer 1

The (small) difference is:
In a while{} loop, the block may never be executed.
In a do{}while loop, the block is always executed at least once.

This can be useful, e.g.

boolean repeat = true;
do{
//do something
//check some result
repeat = need_to_try_again();
}
while(repeat)

Answer 2

For instance in a text calculator. The user is asked whether he wants to go again. This can be put inside a do...while loop.

Answer 3

You ask user for an input, like a password, but it must be at least 6 characters long. Thus, you’ll have to ask him/her the password at least once, and then keep asking for it for as long as you don’t get a valid input. A do-while loop does the job.

Answer 4

do while is very important when you need to put validations on inputs of your program.
i.e. repeatedly ask for the input until a valid input is given.

Answer 5

Perfect. Thank you to both answers.

Answer 6

the do-while loop is used when the statement within the loop must run atleast once. here's some example:
1.If u want to travel by your own vehicle(two wheeler or four wheeler),You should know how much petrol available in your vehicle and you know how much distance to travel (For loop  ---Know the initial condition and no of iterations)

2.If u want to travel in a FLIGHT, You should buy a ticket then only you are eligible to enter into the Flight. (While loop ---- First satisfy the condition then Proceed)

3.If u want to travel in BUS, You can board the bus then buy the ticket. (DO WHILE ---- Proceed first then checking)