A Simple Flutter Calculator App

flutter calculator app

build a calculator app in ios and android with the same code by using flutter.

structure

input widgets

input widgets is all extends statefulwidget, because they need to response the ontap gesture.

• numberbutton. rendering the number button (like 1,2,3…) and handling the ontap gesture.
• operatorbutton. rendering the operator button (like +,-,*…) and handling the ontap gesture.
• resultbutton. rendering the command button (like clear,equal…) and handling the ontap gesture.

output widgets

output widgets is all extends statelesswidget, because they are just rendering.

• resultdisplay. rendering the current result and changing display when user tap a number button.
• historyblock. rendering the calculation histories and changing display every time when user tap a valid button.

calculator page

calculatorpage is extends statefulwidget and holding the list of result.

it receives every input widgets ontap event, makes a logical calculation for these inputs and decides what to display to output widgets.