Article directory
I. Introduction
In the daily programming process, we often encounter the need to round decimals or keep n digits after the decimal point. These requirements are especially common when dealing with scenarios such as data statistics and commodity prices. This article will introduce in detail how to implement these two operations in Flutter, and demonstrate their application through examples.
By reading this article, you will master the following knowledge:
- Numeric types in the Dart language
- Various implementation methods of decimal rounding in Flutter
- The implementation method of retaining n digits after the decimal point in Flutter
- How to handle decimals in practical applications
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2. Numerical types in Dart language
In the Dart language, there are two main types of values: int and double. The int type is used to represent integers, and the double type is used to represent double-precision floating-point numbers, which is what we often call decimals. Both types are subclasses of the num class, which provides some basic math and comparison operations.
In Dart, we can create objects of type int or double through literals or constructors. For example:
int a = 10;
double b = 10.0;
In addition, Dart also provides some methods for conversion between numeric types, such as toInt(), toDouble(), toString(), etc.
3. Implementation of decimal rounding in Flutter
When dealing with decimals, we often need to round them up. In Dart, we can use the following methods to achieve decimal rounding:
1. Use the round method
The round method will round the decimal to the nearest whole number. For example:
double a = 10.5;
int b = a.round();
print(b); // 输出：11
2. Use the toInt method
The toInt method will directly remove the decimal part and only keep the integer part. For example:
double a = 10.5;
int b = a.toInt();
print(b); // 输出：10
3. Use the truncate method
The effect of the truncate method is the same as that of the toInt method, which directly removes the decimal part. For example:
double a = 10.5;
int b = a.truncate();
print(b); // 输出：10
4. The implementation of retaining n digits after the decimal point in Flutter
When dealing with decimals, we sometimes need to keep n digits after the decimal point. In Dart, we can use the following methods to achieve this requirement:
1. Use the toStringAsFixed method
The toStringAsFixed method can convert a number to a string and keep n digits after the decimal point. For example:
double a = 10.123456;
String b = a.toStringAsFixed(2);
print(b); // 输出："10.12"
2. Use the NumberFormat class
The NumberFormat class is a class provided by the intl package that can be used to format numbers. We can use this to keep n decimal places. For example:
import 'package:intl/intl.dart';
double a = 10.123456;
NumberFormat format = NumberFormat("0.00");
String b = format.format(a);
print(b); // 输出："10.12"
The above are several methods for retaining n digits after the decimal point in Flutter, and you can choose the appropriate method according to your actual needs.
5. Practical demonstration: application scenarios of Flutter decimal processing
Below we demonstrate how to handle decimals in Flutter through two practical application scenarios.
1. Handling of commodity prices
In e-commerce applications, we often need to display the price of a product. Since the price usually needs to keep two decimal places, we can use the toStringAsFixed method or the NumberFormat class to handle the price. For example:
double price = 10.123456;
String formattedPrice = price.toStringAsFixed(2);
print(formattedPrice); // 输出："10.12"
2. Processing of data statistics
In data statistics applications, we often need to round the data. For example, we may need to count the average active time of users. This time may be a decimal, but we may only need to display the integer part when displaying. At this time, we can use the round, toInt or truncate method to process the data. For example:
double averageActiveTime = 10.5;
int roundedActiveTime = averageActiveTime.round();
print(roundedActiveTime); // 输出：11
6. Summary
In this article, we introduced in detail how to deal with decimals in Flutter, including how to implement decimal rounding and how to retain n digits after the decimal point. We first introduced the numerical types in the Dart language, and then introduced several methods of rounding decimals and retaining n digits after the decimal point, and demonstrated them through practical application scenarios.
When dealing with decimals, we need to choose the appropriate method according to actual needs. For example, if we need to round to the nearest integer, we can use the round method; if we need to keep n decimal places, we can use the toStringAsFixed method or the NumberFormat class.
This is the blog published by Xiaoyu Youth on CSDN in 2023. Due to the rampant copyright infringement of the collection station, if you do not see this article on CSDN, please contact me through CSDN, thank you for your support~
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