How to avoid floating-point precision loss when performing calculations in a template?
As an experienced website operations expert, I am well aware that it is crucial to ensure the accuracy of data and users' trust in daily work, especially when dealing with data display related to amounts.AnQiCMS (AnQiCMS) offers us powerful content management capabilities with its efficient and flexible features.However, when performing currency calculations and displaying them in templates, a common but easily overlooked problem is the loss of floating-point precision.Today, let's delve deeply into this issue and provide effective and smooth solutions in the AnQiCMS template.
The silent killer in money calculations: floating-point precision loss
First, let's understand what floating-point precision loss is.Inside a computer, most programming languages (including Go language, as well as the AnQiCMS template engine built on it) use binary floating-point numbers to represent decimals.Due to the binary system's inability to accurately represent certain decimal fractions (such as 0.1, 0.2), they are often approximate when stored.This leads to, when we perform addition, subtraction, multiplication, and division operations on these approximate values, the accumulated error may cause the final result to produce a small deviation, for example0.1 + 0.2The result may not be0.3it is not0.30000000000000004.
In the AnQiCMS template environment, we often encounter scenarios where we need to display the total price of goods, member points exchange amount, and the final price after discount calculation. For example, document detail tagsarchiveDetailand document list tagarchiveListprovided inPriceandStocksuch as fields, user detail taguserDetailthere isBalanceandTotalRewarduser group detail taguserGroupDetailthenPriceandFavorablePriceThese fields may contain amounts that need to be calculated.tag-calc.mdIt clearly indicates that the template supports arithmetic operations, such as addition, subtraction, multiplication, division, and floating-point number comparison.This means that if we perform mathematical operations directly on these amount fields in the template, we may encounter a loss of precision, which may affect the accuracy of the final display.
Imagine if the price that users see on the website is29.970000000000002instead of29.97This may make people feel unprofessional, and it may also raise doubts about the reliability of the website's data. As an operator, we must avoid this kind of situation.