In-depth analysis of golang’s lack of precision problem

Golang language has received widespread attention for its good concurrency performance and programming simplicity since its birth. However, when performing numerical calculations, the Golang language suffers from a lack of precision. In this article, we will focus on the problem of lack of accuracy in the Golang language, and explore the causes and solutions.

1. Problem description

When performing floating point number calculations, due to Golang’s underlying processing method, there is often a lack of precision. For example:

a := 0.1
b := 0.2
c := a + b
fmt.Println(c)  // 0.30000000000000004

As you can see from the above example, when performing simple addition operations, there is a slight accuracy error in the calculation results. This kind of error will not have a serious impact on calculations in most cases, but in some high-precision computing scenarios it will lead to inaccurate calculation results of the program.

2. Cause Analysis

The problem of lack of precision in Golang language stems from the limitations of the binary representation of its underlying computer. In computers, floating point numbers are represented using the IEEE754 standard and are represented by binary decimals. However, not all decimal decimals can be completely converted into binary decimals. For example, 0.1 in binary decimal is an infinitely recurring decimal, that is, 0.0001100110011…. Since a computer can only store a limited number of bits in its memory, it can only store a limited number of binary decimals, which leads to a problem of loss of precision.

3. Solution

In order to solve the problem of lack of precision in Golang language, we can adopt the following two solutions:

1. Use the decimal library

## The #decimal library is a high-precision calculation library in Golang language that uses decimal to represent floating point numbers. Using this library can effectively solve the problem of missing precision of floating point numbers. For example:

import (
    "fmt"
    "github.com/shopspring/decimal"
)

func main() {
    a, _ := decimal.NewFromString("0.1")
    b, _ := decimal.NewFromString("0.2")
    c := a.Add(b)
    fmt.Println(c)  // 0.3
}

In the above code example, using the decimal library can completely avoid the problem of missing precision, and the calculation result is 0.3.

2. Use integer calculations

The Golang language can also avoid the problem of lack of precision in floating point numbers by using integer calculations. For example, when you need to perform precise calculations on decimal numbers, you can move the decimal point several places to the right and convert the decimal into an integer for calculation. For example:

a := 1
b := 3
c := 10
d := a * c + b * c / 10    // 将小数点向右移动了1位
fmt.Println(d)  // 13

In the above code example, the decimal point is moved one place to the right and 0.3 is converted into an integer for calculation, thus avoiding the problem of missing precision.

In short, when the Golang language performs floating-point calculations, there is often a problem of lack of precision. In order to solve this problem, we can choose to use the decimal library or integer calculation. These solutions can effectively ensure the accuracy of calculation results and improve the accuracy and stability of the program.

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