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< li >< a href = "file-operations.html" class = "active" > File Operations</ a ></ li >
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< article >
< h1 > File Operations</ h1 >
< h2 > Read Entire File</ h2 >
< pre >< code > import "io" for File
var content = File.read("document.txt")
System.print(content)</ code ></ pre >
< h2 > Write to File</ h2 >
< pre >< code > import "io" for File
File.write("output.txt", "Hello, World!")
System.print("File written!")</ code ></ pre >
< h2 > Append to File</ h2 >
< pre >< code > import "io" for File
var existing = File.exists("log.txt") ? File.read("log.txt") : ""
File.write("log.txt", existing + "New line\n")</ code ></ pre >
< h2 > Check if File Exists</ h2 >
< pre >< code > import "io" for File
if (File.exists("config.txt")) {
System.print("Config found")
var content = File.read("config.txt")
} else {
System.print("Config not found, using defaults")
}</ code ></ pre >
< h2 > Get File Size</ h2 >
< pre >< code > import "io" for File
var size = File.size("data.bin")
System.print("File size: %(size) bytes")</ code ></ pre >
< h2 > Copy File</ h2 >
< pre >< code > import "io" for File
File.copy("source.txt", "destination.txt")
System.print("File copied!")</ code ></ pre >
< h2 > Rename/Move File</ h2 >
< pre >< code > import "io" for File
File.rename("old_name.txt", "new_name.txt")
System.print("File renamed!")
File.rename("file.txt", "subdir/file.txt")
System.print("File moved!")</ code ></ pre >
< h2 > Delete File</ h2 >
< pre >< code > import "io" for File
if (File.exists("temp.txt")) {
File.delete("temp.txt")
System.print("File deleted!")
}</ code ></ pre >
< h2 > List Directory Contents</ h2 >
< pre >< code > import "io" for Directory
var files = Directory.list(".")
for (file in files) {
System.print(file)
}</ code ></ pre >
< h2 > Check if Directory Exists</ h2 >
< pre >< code > import "io" for Directory
if (Directory.exists("data")) {
System.print("Directory found")
} else {
System.print("Directory not found")
}</ code ></ pre >
< h2 > Create Directory</ h2 >
< pre >< code > import "io" for Directory
if (!Directory.exists("output")) {
Directory.create("output")
System.print("Directory created!")
}</ code ></ pre >
< h2 > Delete Empty Directory</ h2 >
< pre >< code > import "io" for Directory
Directory.delete("empty_folder")
System.print("Directory deleted!")</ code ></ pre >
< h2 > Read File Line by Line</ h2 >
< pre >< code > import "io" for File
var content = File.read("data.txt")
var lines = content.split("\n")
for (line in lines) {
if (line.count > 0) {
System.print(line)
}
}</ code ></ pre >
< h2 > Process Files in Directory</ h2 >
< pre >< code > import "io" for File, Directory
var files = Directory.list("./data")
for (filename in files) {
if (filename.endsWith(".txt")) {
var path = "./data/%(filename)"
var content = File.read(path)
System.print("%(filename): %(content.count) chars")
}
}</ code ></ pre >
< h2 > Recursive Directory Listing</ h2 >
< pre >< code > import "io" for File, Directory
var listRecursive = Fn.new { |path, indent|
var items = Directory.list(path)
for (item in items) {
var fullPath = "%(path)/%(item)"
System.print("%(indent)%(item)")
if (Directory.exists(fullPath)) {
listRecursive.call(fullPath, indent + " ")
}
}
}
listRecursive.call(".", "")</ code ></ pre >
< h2 > Find Files by Extension</ h2 >
< pre >< code > import "io" for File, Directory
var findByExtension = Fn.new { |path, ext|
var results = []
var items = Directory.list(path)
for (item in items) {
var fullPath = "%(path)/%(item)"
if (Directory.exists(fullPath)) {
var subResults = findByExtension.call(fullPath, ext)
for (r in subResults) results.add(r)
} else if (item.endsWith(ext)) {
results.add(fullPath)
}
}
return results
}
var wrenFiles = findByExtension.call(".", ".wren")
for (file in wrenFiles) {
System.print(file)
}</ code ></ pre >
< h2 > Read JSON Configuration</ h2 >
< pre >< code > import "io" for File
import "json" for Json
var loadConfig = Fn.new { |path, defaults|
if (!File.exists(path)) {
return defaults
}
var content = File.read(path)
var config = Json.parse(content)
for (key in defaults.keys) {
if (!config.containsKey(key)) {
config[key] = defaults[key]
}
}
return config
}
var config = loadConfig.call("config.json", {
"port": 8080,
"debug": false
})
System.print("Port: %(config["port"])")</ code ></ pre >
< h2 > Save JSON Configuration</ h2 >
< pre >< code > import "io" for File
import "json" for Json
var config = {
"database": "app.db",
"port": 8080,
"debug": true
}
File.write("config.json", Json.stringify(config, 2))
System.print("Configuration saved!")</ code ></ pre >
< h2 > Create Backup Copy</ h2 >
< pre >< code > import "io" for File
import "datetime" for DateTime
var backup = Fn.new { |path|
if (!File.exists(path)) {
System.print("File not found: %(path)")
return null
}
var timestamp = DateTime.now().format("\%Y\%m\%d_\%H\%M\%S")
var backupPath = "%(path).%(timestamp).bak"
File.copy(path, backupPath)
System.print("Backup created: %(backupPath)")
return backupPath
}
backup.call("important.txt")</ code ></ pre >
< h2 > Read User Input</ h2 >
< pre >< code > import "io" for Stdin
System.write("Enter your name: ")
var name = Stdin.readLine()
System.print("Hello, %(name)!")</ code ></ pre >
< h2 > Interactive Menu</ h2 >
< pre >< code > import "io" for Stdin
System.print("Select an option:")
System.print("1. Option A")
System.print("2. Option B")
System.print("3. Exit")
System.write("Choice: ")
var choice = Stdin.readLine()
if (choice == "1") {
System.print("You selected Option A")
} else if (choice == "2") {
System.print("You selected Option B")
} else if (choice == "3") {
System.print("Goodbye!")
}</ code ></ pre >
< h2 > Safe File Operations with Error Handling</ h2 >
< pre >< code > import "io" for File
var safeRead = Fn.new { |path|
var fiber = Fiber.new { File.read(path) }
var result = fiber.try()
if (fiber.error) {
System.print("Error reading %(path): %(fiber.error)")
return null
}
return result
}
var content = safeRead.call("maybe_exists.txt")
if (content) {
System.print("Content: %(content)")
}</ code ></ pre >
< h2 > Calculate Directory Size</ h2 >
< pre >< code > import "io" for File, Directory
var dirSize = Fn.new { |path|
var total = 0
var items = Directory.list(path)
for (item in items) {
var fullPath = "%(path)/%(item)"
if (Directory.exists(fullPath)) {
total = total + dirSize.call(fullPath)
} else if (File.exists(fullPath)) {
total = total + File.size(fullPath)
}
}
return total
}
var size = dirSize.call(".")
System.print("Total size: %(size) bytes")</ code ></ pre >
< div class = "admonition tip" >
< div class = "admonition-title" > See Also</ div >
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< p > For full API documentation, see the < a href = "../api/io.html" > IO module reference</ a > . For object-oriented path manipulation with glob, walk, and tree operations, see the < a href = "../api/pathlib.html" > pathlib module reference</ a > .</ p >
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</ article >
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