SmartPhoneCalculator (OnePlus Calculator)

Features

1. Operator Restriction:

   • You cannot press any operation button more than once consecutively. For example, entering 1++++ or 7--- or 18** or 9÷÷ is prevented, ensuring valid mathematical expressions.

2. Initial Operator Validation:

   • You cannot start an expression with an operator other than minus (-). This means expressions like +1, *1, or /1 are invalid, maintaining proper input syntax from the start.

3. AC Button Functionality:

   • When the AC (All Clear) button is clicked, the display shows zero (0), mimicking the behavior of a smartphone calculator. Unlike other calculators that might show a blank screen, this feature provides a consistent and familiar user experience.

4. Delete Button Behavior:

   • When you delete the last number in the input, the display automatically shows zero (0), similar to the AC button functionality. This ensures the display is never left blank and always maintains a user-friendly state.

Usage

• Basic Operations: Perform addition, subtraction, multiplication, and division as with any standard calculator.
• Clear Entry: Use the AC button to reset the calculator and display zero (0).
• Delete Entry: Use the delete button to remove the last digit. If the last digit is removed, the display will revert to zero (0).

Example Scenarios

1. Prevent Consecutive Operators:

   • Input: 5++++ or 7-- or 18** or 22÷÷ etc...
   • Result: Only one + or - or * or ÷ is accepted, preventing invalid expression 5++++.

2. Valid Initial Input:

   • Input: +8+1 or *8-1 or ÷18*4 etc are invalid inputs.
   • Result: The input is corrected to prevent starting with + or * or ÷.

3. AC Button Usage:

   • Action: Press the AC button
   • Result: The display shows 0.

4. Delete Button Usage:

   • Input: 123
   • Action: Press the delete button three times
   • Result: The display shows 0.

This calculator provides a more sophisticated and intuitive interface, ensuring users can perform calculations easily while preventing common input errors.