├── calc.PNG
├── main.dart
├── pubspec.yaml
└── readme.md


/calc.PNG:
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https://raw.githubusercontent.com/chandran-jr/Calculator/7451d7dab47f522c64a3949441c55e98b088f0cb/calc.PNG


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/main.dart:
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  1 | import 'package:flutter/cupertino.dart';
  2 | import 'package:flutter/material.dart';
  3 | import 'package:math_expressions/math_expressions.dart';
  4 | 
  5 | void main(){
  6 |   runApp(Calculator());
  7 | 
  8 | }
  9 | 
 10 | class Calculator extends  StatelessWidget{
 11 |   @override
 12 |   Widget build(BuildContext context){
 13 |     return MaterialApp(
 14 |       debugShowCheckedModeBanner: false,
 15 |       title: 'Calculator',
 16 |       theme:ThemeData(primarySwatch: Colors.green),
 17 |       home: SimpleCalculator(),
 18 |     );
 19 |   }
 20 | }
 21 | 
 22 | class SimpleCalculator extends StatefulWidget{
 23 |   @override
 24 | _SimpleCalculatorState createState() => _SimpleCalculatorState();
 25 | }
 26 | 
 27 | class _SimpleCalculatorState extends State<SimpleCalculator> {
 28 | 
 29 |   String equation = "0";
 30 |   String result = "0";
 31 |   String expression = "";
 32 |   double equationFontSize = 38.0;
 33 |   double resultFontSize = 48.0;
 34 | 
 35 |   buttonPressed(String buttonText){
 36 |     setState(() {
 37 |       if(buttonText=="C"){
 38 |         equation="0";
 39 |         result="0";
 40 |         equationFontSize = 38.0;
 41 |         resultFontSize = 48.0;
 42 |       }
 43 |       else if(buttonText=="DEL"){
 44 |         equationFontSize = 48.0;
 45 |         resultFontSize = 38.0;
 46 |         equation = equation.substring(0, equation.length - 1);
 47 |         if(equation==""){
 48 |           equation="0";
 49 |         }
 50 |       }
 51 |       else if(buttonText=="="){
 52 |         equationFontSize = 38.0;
 53 |         resultFontSize = 48.0;
 54 |         expression = equation;
 55 | 
 56 |         try{
 57 |           Parser p = Parser();
 58 |           Expression exp = p.parse(expression);
 59 | 
 60 |           ContextModel cm = ContextModel();
 61 |           result = '${exp.evaluate(EvaluationType.REAL, cm)}';
 62 | 
 63 |         }catch(e){
 64 |           result="Error";
 65 |         }
 66 | 
 67 | 
 68 |       }
 69 |       else {
 70 |         equationFontSize = 48.0;
 71 |         resultFontSize = 38.0;
 72 |         if (equation == "0") {
 73 |           equation = buttonText;
 74 |         }
 75 |         else {
 76 |           equation = equation + buttonText;
 77 |         }
 78 |       }});
 79 | 
 80 |   }
 81 | 
 82 | 
 83 | 
 84 |   Widget buildButton(String buttonText,double buttonHeight, Color buttonColor){
 85 |     return Container(
 86 |       height: MediaQuery.of(context).size.height*0.1*buttonHeight,
 87 |       color: buttonColor,
 88 |       child: FlatButton(
 89 |           shape: RoundedRectangleBorder(
 90 |               borderRadius: BorderRadius.circular(0.0),
 91 |               side: BorderSide(
 92 |                   color: Colors.white,
 93 |                   width: 1,
 94 |                   style: BorderStyle.solid
 95 |               )
 96 |           ),
 97 |           padding: EdgeInsets.all(16.0),
 98 |           onPressed: () => buttonPressed(buttonText),
 99 |           child: Text(
100 |             buttonText,
101 |             style: TextStyle(
102 |                 fontSize: 30.0,
103 |                 fontWeight: FontWeight.normal,
104 |                 color: Colors.white
105 |             ),
106 |           )
107 |       ),
108 |     );
109 |   }
110 |   @override
111 | Widget build(BuildContext context) {
112 |     // TODO: implement build
113 |     return Scaffold(
114 |       appBar: AppBar(title: Text('Calculator')),
115 |       body: Column(
116 |         children: <Widget>[
117 |           Container(
118 |             alignment: Alignment.centerRight,
119 |             padding: EdgeInsets.fromLTRB(10, 20, 10, 0),
120 |             child: Text(equation,style: TextStyle(fontSize: equationFontSize),),
121 |           ),
122 |           Container(
123 |             alignment: Alignment.centerRight,
124 |             padding: EdgeInsets.fromLTRB(10, 20, 10, 0),
125 |             child: Text(result,style: TextStyle(fontSize: resultFontSize),),
126 |           ),
127 |           Expanded(
128 |             child: Divider(),
129 |           ),
130 |           Row(
131 |             mainAxisAlignment: MainAxisAlignment.center,
132 |             children: <Widget>[
133 |               Container(
134 |                 width: MediaQuery.of(context).size.width*0.75,
135 |                 child: Table(
136 |                   children: [
137 |                     TableRow(
138 |                       children: [
139 |                         buildButton("C", 1, Colors.redAccent),
140 |                         buildButton("DEL", 1, Colors.redAccent),
141 |                         buildButton("/", 1, Colors.blue),
142 |                       ]
143 |                     ),
144 | 
145 |                     TableRow(
146 |                         children: [
147 |                           buildButton("7", 1, Colors.black54),
148 |                           buildButton("8", 1, Colors.black54),
149 |                           buildButton("9", 1, Colors.black54),
150 |                         ]
151 |                     ),
152 | 
153 |                     TableRow(
154 |                         children: [
155 |                           buildButton("4", 1, Colors.black54),
156 |                           buildButton("5", 1, Colors.black54),
157 |                           buildButton("6", 1, Colors.black54),
158 |                         ]
159 |                     ),
160 | 
161 |                     TableRow(
162 |                         children: [
163 |                           buildButton("1", 1, Colors.black54),
164 |                           buildButton("2", 1, Colors.black54),
165 |                           buildButton("3", 1, Colors.black54),
166 |                         ]
167 |                     ),
168 | 
169 |                     TableRow(
170 |                         children: [
171 |                           buildButton(".", 1, Colors.black54),
172 |                           buildButton("0", 1, Colors.black54),
173 |                           buildButton("00", 1, Colors.black54),
174 |                         ]
175 |                     ),
176 |                   ],
177 |                 ),
178 |               ),
179 | 
180 | 
181 |               Container(
182 |                 width: MediaQuery.of(context).size.width*0.25,
183 |                 child: Table(
184 |                   children: [
185 |                     TableRow(
186 |                       children: [
187 |                         buildButton("*", 1, Colors.blue),
188 |                       ]
189 |                     ),
190 | 
191 |                     TableRow(
192 |                         children: [
193 |                           buildButton("-", 1, Colors.blue),
194 |                         ]
195 |                     ),
196 | 
197 |                     TableRow(
198 |                         children: [
199 |                           buildButton("+", 1, Colors.blue),
200 |                         ]
201 |                     ),
202 | 
203 |                     TableRow(
204 |                         children: [
205 |                           buildButton("=", 2, Colors.green),
206 |                         ]
207 |                     ),
208 |                   ],
209 |                 ),
210 |               )
211 |             ],
212 |           ),
213 |         ],
214 |       ),
215 | 
216 |     );
217 |   }
218 | }
219 | 


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/pubspec.yaml:
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 1 | name: calc
 2 | description: A Calculator app using flutter.
 3 | 
 4 | # The following defines the version and build number for your application.
 5 | # A version number is three numbers separated by dots, like 1.2.43
 6 | # followed by an optional build number separated by a +.
 7 | # Both the version and the builder number may be overridden in flutter
 8 | # build by specifying --build-name and --build-number, respectively.
 9 | # In Android, build-name is used as versionName while build-number used as versionCode.
10 | # Read more about Android versioning at https://developer.android.com/studio/publish/versioning
11 | # In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
12 | # Read more about iOS versioning at
13 | # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
14 | version: 1.0.0+1
15 | 
16 | environment:
17 |   sdk: ">=2.1.0 <3.0.0"
18 | 
19 | dependencies:
20 |   flutter:
21 |     sdk: flutter
22 | 
23 |   # The following adds the Cupertino Icons font to your application.
24 |   # Use with the CupertinoIcons class for iOS style icons.
25 |   cupertino_icons: ^0.1.2
26 |   math_expressions: ^2.0.0
27 | 
28 | dev_dependencies:
29 |   flutter_test:
30 |     sdk: flutter
31 | 
32 | 
33 | # For information on the generic Dart part of this file, see the
34 | # following page: https://dart.dev/tools/pub/pubspec
35 | 
36 | # The following section is specific to Flutter.
37 | flutter:
38 | 
39 |   # The following line ensures that the Material Icons font is
40 |   # included with your application, so that you can use the icons in
41 |   # the material Icons class.
42 |   uses-material-design: true
43 | 
44 |   # To add assets to your application, add an assets section, like this:
45 |   # assets:
46 |   #  - images/a_dot_burr.jpeg
47 |   #  - images/a_dot_ham.jpeg
48 | 
49 |   # An image asset can refer to one or more resolution-specific "variants", see
50 |   # https://flutter.dev/assets-and-images/#resolution-aware.
51 | 
52 |   # For details regarding adding assets from package dependencies, see
53 |   # https://flutter.dev/assets-and-images/#from-packages
54 | 
55 |   # To add custom fonts to your application, add a fonts section here,
56 |   # in this "flutter" section. Each entry in this list should have a
57 |   # "family" key with the font family name, and a "fonts" key with a
58 |   # list giving the asset and other descriptors for the font. For
59 |   # example:
60 |   # fonts:
61 |   #   - family: Schyler
62 |   #     fonts:
63 |   #       - asset: fonts/Schyler-Regular.ttf
64 |   #       - asset: fonts/Schyler-Italic.ttf
65 |   #         style: italic
66 |   #   - family: Trajan Pro
67 |   #     fonts:
68 |   #       - asset: fonts/TrajanPro.ttf
69 |   #       - asset: fonts/TrajanPro_Bold.ttf
70 |   #         weight: 700
71 |   #
72 |   # For details regarding fonts from package dependencies,
73 |   # see https://flutter.dev/custom-fonts/#from-packages
74 | 


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/readme.md:
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 1 | # A simple calculator app 
 2 | 
 3 | **I used:**
 4 | * Cupertino icons
 5 | * Math operations
 6 | 
 7 | 
 8 | **Preview:**
 9 | 
10 | <img src= "calc.PNG">
11 | 


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