using loops ie for,while or do while .to check..for login input data validity

Question

Username must match as before
So should the password

Answer 1

have you try writing some code for this, if(true) show it; else try write some, users here don't write code for others but help em fix it

Answer 2

If you were asking which loop is more suitable for login information validation scenarios, then I recommend do...while loop. Why? because this loop goes at least once before it evaluates the loop condition validity. You normally get the credentials at least once, check for credentials validity, and loop while it's not valid, or exit the loop if credentials are valid.
Implementation is in your hand, nonetheless tup

Answer 3

You can also "switch" also for this.