dart - 删除两位小数后的数字而不四舍五入其值？

Question

var num1 = 10.12345678

我应该如何处理 num1 以删除小数点后两位数字而不对其值进行四舍五入。
我需要输出为 10.12

import 'package:flutter/material.dart';

void main() => runApp(MaterialApp(
      title: ' Delete digits after two decimal point ',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: MyHome(),
    ));

class MyHome extends StatefulWidget {
  @override
  _MyHomeState createState() => _MyHomeState();
}

class _MyHomeState extends State<MyHome> {
    @override
  Widget build(BuildContext context) {

    var num1 = 10.12345678;
    print(num1); // I need output as 10.12

    return Container();
  }

}

Answer 1

如果要对数字进行四舍五入:

var num1 = 10.12345678;
var num2 = double.parse(num1.toStringAsFixed(2)); // num2 = 10.12

---

如果您不想对数字进行四舍五入:

创建这个方法:

double getNumber(double input, {int precision = 2}) => 
  double.parse('$input'.substring(0, '$input'.indexOf('.') + precision + 1));

用法:

var input = 113.39999999999999;
var output = getNumber(input, precision: 1); // 113.9
var output = getNumber(input, precision: 2); // 113.99
var output = getNumber(input, precision: 3); // 113.999