As an experienced website operations expert, I know that ensuring the accuracy of data and the trust of users is crucial, especially when dealing with data display related to amounts in daily work.AnQiCMS (AnQiCMS) provides us with powerful content management capabilities with its high efficiency and flexibility.However, a common but often overlooked issue when performing and displaying monetary calculations in templates is 'loss of floating-point precision'.Today, let's delve deeply into this issue and provide effective and fluent solutions in the AnQiCMS template.
The silent killer in amount calculation: Floating-point precision loss
Firstly, 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 values when stored.0.1 + 0.2The result may not be0.3but instead0.30000000000000004.
In the template environment of AnQiCMS, we often encounter scenarios where we need to display the total price of goods, the amount of member points for exchange, and the final price after discount calculation. For example, document detail tagsarchiveDetailWith document list tagsarchiveListare providedPriceandStocksuch as fields, user details taguserDetailhasBalanceandTotalRewardand user group details taguserGroupDetailthere isPriceandFavorablePrice. These fields may contain amounts that need to be calculated.tag-calc.mdClearly 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, there is a possibility of losing precision, which may affect the accuracy of the final display.
Imagine if the price the user sees on the website is29.970000000000002instead of29.97This may not only make people feel unprofessional, but it is also likely to raise doubts about the reliability of the website's data. As an operator, we must avoid this kind of situation.