Tags
#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
#python
#files
#utils
#strings
#http
#concurrency
#async
#json
#arrays
#security
#types
#crypto
#database
#dates
#format
Go
filepath.Walk — Recursive Tree Walk
`filepath.WalkDir` (Go 1.16+) is the modern, faster version. Visit every file/dir under a root; the callback decides whether to skip or process.
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PHP
Recursive Directory Walker
Yield every file under a directory using a generator and SPL's RecursiveIteratorIterator. Filter by extension or any other predicate without slurping all paths into memory first.
Java
Files.walk — Recursive Tree Traversal
`Files.walk` returns a lazy Stream over every entry under a path. Filter with stream operations; remember to close the stream (or use try-with-resources).
Python
Walk Directory Tree (Filtered)
Recursively yield every file under a directory matching a predicate. Built on pathlib.rglob; the predicate gives you precise control without listing the whole tree up front.
Kotlin
use { } — Auto-Close Resources
`use { }` calls `close()` on any `Closeable` (file, stream, JDBC connection, …) when the block exits — even on exception. Kotlin's try-with-resources.
Kotlin
Path Operations with java.nio.file
Modern Kotlin code uses `java.nio.file.Path` over the legacy `File`. Operator overloads + Kotlin extensions make it ergonomic.
Rust
Read a File — Whole / Lines / Bytes
Three common patterns: load it all into memory, iterate line-by-line, or stream bytes. Pick by file size — `read_to_string` is convenient but bad for huge files.
Python
Stream Large CSV with DictReader
Iterate over a CSV row-by-row as a dict — never loading the whole file. Tolerant of UTF-8 BOMs (utf-8-sig). Generator wrapper makes consumers naturally use for/break.
Bash
Tail Last N Lines (no `tail` shortcuts)
`tail -n 20` works for any case where tail is available. The pure-bash version below is useful inside containers or rescue shells where coreutils is missing.
JavaScript
Download File from Client
Programmatically triggers a file download from a Blob, File object, or plain text/JSON string without a server round-trip. Creates a temporary anchor element with a download attribute and revokes the object URL after use to prevent memory leaks. Supports custom filenames and MIME types.
JavaScript
Format File Size
Converts a raw byte count into a human-readable string with the appropriate unit (B, KB, MB, GB, TB). Uses 1024-based (binary) units by default or optionally 1000-based (SI) units. Useful for upload progress indicators, file browsers, and storage dashboards.
PHP
Stream Large CSV with Generator
Iterate over a CSV file row-by-row without ever loading the whole file into memory. Uses a generator so consumers can foreach naturally and PHP cleans up the file handle.
PHP
Human-Readable File Size
Format a byte count as a human-friendly string (KB / MB / GB / TB). Defaults to base-1024 sizes; pass base 1000 for SI units.
Rust
CSV Read/Write with the csv Crate
`csv` + `serde` lets you read/write CSVs directly into typed structs. No manual field parsing; column order tolerant via headers.
Bash
Recursive Directory Walker with Predicate
Use `find -print0` + `read -d ""` to safely iterate filenames that may contain spaces, newlines, or quotes. Standard bash for-loop over `find` output breaks on these.
Rust
Walk a Directory Tree
`walkdir` recursively iterates every entry under a path, skipping inaccessible directories cleanly. The standard-library alternative requires manual recursion.
PHP
Safe Path Join
Concatenate path segments and produce a normalized canonical path that resists "../" escape attempts. Throws if the result would land outside the given base directory.