16 Go interview questions on more standard library essentials, with detailed answers and code.
You implement heap.Interface (which embeds sort.Interface , so Len , Less and Swap , plus Push(any) and Pop() any ). Then you call the package functions heap.Init ,…
Stable: sort.SliceStable , sort.Stable and slices.SortStableFunc . Not stable: sort.Slice , sort.Sort , slices.Sort and slices.SortFunc , which all use pdqsort since Go…
You write a layout by showing how the reference time 01/02 03:04:05PM '06 -0700 would look in your format: 1=month, 2=day, 3/15=hour, 4=minute, 5=second, 6=year, 7=zone.…
math/rand and math/rand/v2 are fast pseudo-random generators whose output can be predicted . crypto/rand reads from the OS CSPRNG (getrandom, BCryptGenRandom and so on).…
The two packages share the same syntax. text/template does no escaping . html/template parses the HTML around each action and works out its context : element body,…
Always pass user values as arguments to QueryContext , ExecContext or QueryRowContext , and never build SQL with fmt.Sprintf or + . The driver sends the query and the…
== and bytes.Equal return as soon as they hit the first byte that differs. By measuring response times over many requests, an attacker can recover a token or HMAC byte…
Go's regexp uses RE2 syntax and automata-based matching (a Thompson NFA, a one-pass matcher and a bounded backtracker). It guarantees matching in O(m·n) time , linear in…
exec.Command(name, args...) runs the program directly (execve or CreateProcess). No shell is involved, so ; , | , $() and globs inside arguments are just literal bytes.…
The pattern: Call Accept in a loop. Start one goroutine per connection. Set deadlines on every read and write so that slow or idle clients cannot pin goroutines forever.…
fs.FS (Go 1.16) is a minimal read-only interface: Open(name string) (fs.File, error) . Optional interfaces add capabilities: ReadDirFS , ReadFileFS , StatFS , SubFS and…
os.OpenRoot(dir) returns an *os.Root . All of its operations ( Open , Create , OpenFile , Mkdir , Remove , Stat , Lstat , plus ReadFile , WriteFile , MkdirAll , Rename ,…
You define flags ( flag.Int , flag.StringVar , flag.Func , flag.TextVar , flag.BoolFunc ), call flag.Parse() once in main , and read flag.Args() for the positional…
strconv is type-specific and does not allocate for parsing. It returns precise errors and is several times faster than fmt.Sprintf("%d") or fmt.Sscan , which go through…
encoding/binary: fixed-layout binary protocols and file formats (network headers, on-disk records, hashing inputs) where you control every byte. There is no schema and…
The runtime receives OS signals and, for each signal you registered with signal.Notify(ch, sigs...) , forwards it to your channel instead of doing the default action…