Go simplifies file operations, using os.ReadFile to read file content, os.WriteFile to write or overwrite files, os.OpenFile to cooperate with os.O_APPEND to implement additional writing, check whether the file exists through os.Stat, os.Create to create a new file, os.Remove to delete the file, and always need to handle errors and close the file with defer.
Working with file I/O in Go is straightforward thanks to the os and io/ioutil (now largely replaced by io and os packages in modern Go) packages. Here's how to perform common file operations in Go.
Reading a File
To read the entire content of a file, use os.ReadFile (introduced in Go 1.16), which simplifies reading without needing to manually manage file handles.
Example:
content, err := os.ReadFile("example.txt")
if err != nil {
log.Fatal(err)
}
fmt.Println(string(content))
If you need more control, such as reading line by line, use bufio.Scanner .
file, err := os.Open("example.txt")
if err != nil {
log.Fatal(err)
}
defer file.Close()
scanner := bufio.NewScanner(file)
for scanner.Scan() {
fmt.Println(scanner.Text())
}
if err := scanner.Err(); err != nil {
log.Fatal(err)
}
Writing to a File
To write a string or byte slice to a file, use os.WriteFile . This overwrites the file if it exists or creates it if it doesn't.
data := []byte("Hello, World!\n")
err := os.WriteFile("output.txt", data, 0644)
if err != nil {
log.Fatal(err)
}
To append to a file, open it with os.O_APPEND | os.O_CREATE | os.O_WRONLY .
file, err := os.OpenFile("output.txt", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
log.Fatal(err)
}
defer file.Close()
if _, err := file.WriteString("New line\n"); err != nil {
log.Fatal(err)
}
Checking if a File Exists
Go doesn't have a direct Exists function. Use os.Stat and check the error.
if _, err := os.Stat("example.txt"); err == nil {
fmt.Println("File exists")
} else if os.IsNotExist(err) {
fmt.Println("File does not exist")
} else {
fmt.Printf("Error: %v\n", err)
}
Creating and Removing Files
Create an empty file using os.Create , which truncates the file if it already exists.
file, err := os.Create("newfile.txt")
if err != nil {
log.Fatal(err)
}
defer file.Close()
Delete a file using os.Remove .
err := os.Remove("unwanted.txt")
if err != nil {
log.Fatal(err)
}
Basically just use the right function for the job—reading, writing, checking, or managing files—and always handle errors. Go's standard library makes file I/O simple and safe when you follow patterns like deferring Close and checking errors.
The above is the detailed content of How to perform file I/O operations in golang. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
ArtGPT
AI image generator for creative art from text prompts.
Stock Market GPT
AI powered investment research for smarter decisions
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
How do you read and write files in Golang?
Sep 21, 2025 am 01:59 AM
Goprovidessimpleandefficientfilehandlingusingtheosandbufiopackages.Toreadasmallfileentirely,useos.ReadFile,whichloadsthecontentintomemorysafelyandautomaticallymanagesfileoperations.Forlargefilesorincrementalprocessing,bufio.Scannerallowsline-by-liner
What is the empty struct struct{} used for in Golang
Sep 18, 2025 am 05:47 AM
struct{} is a fieldless structure in Go, which occupies zero bytes and is often used in scenarios where data is not required. It is used as a signal in the channel, such as goroutine synchronization; 2. Used as a collection of value types of maps to achieve key existence checks in efficient memory; 3. Definable stateless method receivers, suitable for dependency injection or organization functions. This type is widely used to express control flow and clear intentions.
How do you handle graceful shutdowns in a Golang application?
Sep 21, 2025 am 02:30 AM
GracefulshutdownsinGoapplicationsareessentialforreliability,achievedbyinterceptingOSsignalslikeSIGINTandSIGTERMusingtheos/signalpackagetoinitiateshutdownprocedures,thenstoppingHTTPserversgracefullywithhttp.Server’sShutdown()methodtoallowactiverequest
What is CGO and when to use it in Golang
Sep 21, 2025 am 02:55 AM
CGOenablesGotocallCcode,allowingintegrationwithClibrarieslikeOpenSSL,accesstolow-levelsystemAPIs,andperformanceoptimization;itrequiresimporting"C"withCheadersincomments,usesC.function()syntax,anddemandscarefulmemorymanagement.However,CGOinc
How to read configuration from files in Golang
Sep 18, 2025 am 05:26 AM
Use the encoding/json package of the standard library to read the JSON configuration file; 2. Use the gopkg.in/yaml.v3 library to read the YAML format configuration; 3. Use the os.Getenv or godotenv library to overwrite the file configuration; 4. Use the Viper library to support advanced functions such as multi-format configuration, environment variables, automatic reloading; it is necessary to define the structure to ensure type safety, properly handle file and parsing errors, correctly use the structure tag mapping fields, avoid hard-coded paths, and recommend using environment variables or safe configuration storage in the production environment. It can start with simple JSON and migrate to Viper when the requirements are complex.
Go language strconv package: correct posture for integer to string conversion and the errors of Itoa64
Sep 21, 2025 am 08:36 AM
This article aims to resolve the "undefined" error encountered in Go when trying to use strconv.Itoa64 for integer-to-string conversion. We will explain why Itoa64 does not exist and give details on the correct alternative to strconv.FormatInt in the strconv package. Through instance code, readers will learn how to efficiently and accurately convert integer types into string representations in specified partitions, avoid common programming traps and improve code robustness and readability.
How to use sqlc to generate type-safe SQL code in Go
Sep 17, 2025 am 12:41 AM
Install the sqlcCLI tool, it is recommended to use curl scripts or Homebrew; 2. Create a project structure, including db/schema.sql (table structure), db/query.sql (annotated query) and sqlc.yaml configuration files; 3. Define database tables in schema.sql; 4. Write SQL queries with --name:annotation and :exec/:one/:many directives in query.sqlc.yaml; 5. Configure sqlc.yaml to specify package paths, query files, schema files, database engines and generation options; 6. Run sqlcgenerate to generate type-safe Go code, including models, query methods and interfaces
How to create a custom marshaller/unmarshaller for JSON in Golang
Sep 19, 2025 am 12:01 AM
Implements JSON serialization and deserialization of customizable Go structures for MarshalJSON and UnmarshalJSON, suitable for handling non-standard formats or compatible with old data. 2. Control the output structure through MarshalJSON, such as converting field formats; 3. Parsing special format data through UnmarshalJSON, such as custom dates; 4. Pay attention to avoid infinite loops caused by recursive calls, and use type alias to bypass custom methods.
