Do while loop

Question

I understand how does a do while loop works, it first runs the code once then check the condition.

What is the purpose of a 'do while loop' and is there any real life examples?

Thank you

Answer 1

Like Taste has shown, do-while loops are really great when receiving and validating input, and the reason is because when you are accepting input, you are ALWAYS receiving 1 input at the minimum.

Answer 2

Imagine you want to validate user input. If there is no do while loop (like in python where a do while loop doesn't exist), you have to do this (pseudocode):

input = getUserInput();

while(input != valid) {
input = getUserInput();
}

So you have to write the line "input = getUserInput();" twice.

With a do while loop, you can simply do:

do {
input = getUserInput();
} while (input != valid);

Now you have to write the line "input = getUserInput()" only once and if the while condition is false (i.e. if the user input is valid), there will be no loop that keeps asking for valid input.

Answer 3

Really simple use of do while
do{
cout<<"num :";
cin>>x;
}while(x<1);
It'll keep asking until the user give positive non zero input

Answer 4

Hlo Zahraddeen Mahmud..if u have studied loops then i'll must say u should also know about what r foreach loops..so i have derived foreach loop in c++ using #define preprocessor directive

https://code.sololearn.com/cl5dRAoh6kaa/?ref=app

Answer 5

you could use a do while loop to get password input

example in java:
String password = "12345678";
do {
String input;
Scanner sc = new Scanner(System.in);
input = sc.nextLine();
sc.close();
} while (input != password);
System.out.print("Access granted");

of course you shouldn't use this VERY VERY UNSAFE implementation, but this would be a possibility
also never store passwords in plain text