Home Backend Development Golang Why Do Floating-Point Comparisons in Go Sometimes Yield Unexpected Results?

Why Do Floating-Point Comparisons in Go Sometimes Yield Unexpected Results?

Dec 04, 2024 am 11:33 AM

Why Do Floating-Point Comparisons in Go Sometimes Yield Unexpected Results?

Floating-Point Precision Differences in Go: Constants vs. Variables

In Go, floating-point literals and constants maintain arbitrary precision until assigned to a specific type. However, certain operations and assignments introduce precision differences that can be unexpected.

Consider the following code:

package main

import (
    "fmt"
)

func main() {
    x := 10.1

    fmt.Println("x == 10.1:        ", x == 10.1)
    fmt.Println("x*3.0 == 10.1*3.0:", x*3.0 == 10.1*3.0)
}
Copy after login

This code produces the output:

x == 10.1:         true
x*3.0 == 10.1*3.0: false
Copy after login

Why are these expressions not equal, despite performing the same floating-point operation?

Untyped Constants and Variables

Number literals and constants in Go are untyped, with unlimited precision. Upon assignment to a variable, such as x := 10.1, the literal is converted to the variable's type (float64 in this case) and loses some precision.

Full Precision Constants

In contrast, literal expressions like 10.1*3.0 maintain full precision before evaluation. When assigned to a variable, they are immediately converted to the variable's type, ensuring precision is maintained.

Precision Considerations

Understanding the differences in precision handling can be crucial for accurate floating-point calculations. For example, when comparing values to a specified tolerance, it is important to use literals or expressions with full precision to avoid false positives.

Documentation

This behavior is well-documented in the Go blog article "Constants" under the "Floats" header, which explains that while numeric constants have arbitrary precision, they must fit within the range of the variable they are assigned to.

Conclusion

The difference in precision between floating-point constants vs. variables in Go is by design, allowing for greater flexibility and performance trade-offs in floating-point operations. By understanding these precision differences, programmers can optimize their code for accuracy and efficiency.

The above is the detailed content of Why Do Floating-Point Comparisons in Go Sometimes Yield Unexpected Results?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot Article

Hot Article

Hot Article Tags

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Go language pack import: What is the difference between underscore and without underscore? Go language pack import: What is the difference between underscore and without underscore? Mar 03, 2025 pm 05:17 PM

Go language pack import: What is the difference between underscore and without underscore?

How do I write mock objects and stubs for testing in Go? How do I write mock objects and stubs for testing in Go? Mar 10, 2025 pm 05:38 PM

How do I write mock objects and stubs for testing in Go?

How to implement short-term information transfer between pages in the Beego framework? How to implement short-term information transfer between pages in the Beego framework? Mar 03, 2025 pm 05:22 PM

How to implement short-term information transfer between pages in the Beego framework?

How can I define custom type constraints for generics in Go? How can I define custom type constraints for generics in Go? Mar 10, 2025 pm 03:20 PM

How can I define custom type constraints for generics in Go?

How can I use tracing tools to understand the execution flow of my Go applications? How can I use tracing tools to understand the execution flow of my Go applications? Mar 10, 2025 pm 05:36 PM

How can I use tracing tools to understand the execution flow of my Go applications?

How can I use linters and static analysis tools to improve the quality and maintainability of my Go code? How can I use linters and static analysis tools to improve the quality and maintainability of my Go code? Mar 10, 2025 pm 05:38 PM

How can I use linters and static analysis tools to improve the quality and maintainability of my Go code?

How to write files in Go language conveniently? How to write files in Go language conveniently? Mar 03, 2025 pm 05:15 PM

How to write files in Go language conveniently?

How to convert MySQL query result List into a custom structure slice in Go language? How to convert MySQL query result List into a custom structure slice in Go language? Mar 03, 2025 pm 05:18 PM

How to convert MySQL query result List into a custom structure slice in Go language?

See all articles