Date APIs by Language

C standard library <time.h>

Use time() for Unix seconds, localtime() / gmtime() for struct tm , then strftime() to format.

time_t now = time(NULL);
struct tm *lt = localtime(&now);
char buf[64];
strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", lt);

C++11+: use <chrono> and std::put_time with the same specifiers as strftime .

Python datetime

datetime.now() for the current moment; strftime() to format, strptime() to parse strings.

from datetime import datetime, timezone

now = datetime.now()
now.strftime("%Y-%m-%d %H:%M:%S")
datetime.strptime("2026-05-23", "%Y-%m-%d")
datetime.now(timezone.utc).isoformat()

For time zones prefer zoneinfo (3.9+) or pytz .

JavaScript Date / Intl

Built-in Date for instants; prefer Intl.DateTimeFormat for locale output with a timeZone option.

const now = new Date();
now.toISOString();
now.toLocaleString("en-US");
new Intl.DateTimeFormat("en-US", {
  timeZone: "Asia/Shanghai",
  dateStyle: "full",
  timeStyle: "medium",
}).format(now);
Math.floor(now.getTime() / 1000);

Java java.time (Java 8+)

Prefer Instant , ZonedDateTime , and DateTimeFormatter over legacy Date / Calendar .

import java.time.*;
import java.time.format.DateTimeFormatter;

ZonedDateTime zdt = ZonedDateTime.now(ZoneId.of("Asia/Shanghai"));
zdt.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
Instant.now().getEpochSecond();
LocalDate.parse("2026-05-23");

Go time package

time.Now() returns Time ; Format / Parse use the reference layout Mon Jan 2 15:04:05 MST 2006 .

import "time"

now := time.Now()
now.Format("2006-01-02 15:04:05")
time.Parse("2006-01-02", "2026-05-23")
now.Unix()
time.LoadLocation("Asia/Shanghai")

PHP date functions

date() formats the current time; DateTime / DateTimeImmutable for object-oriented use.

date("Y-m-d H:i:s");
$dt = new DateTime("now", new DateTimeZone("Asia/Shanghai"));
$dt->format("Y-m-d H:i:s");
DateTime::createFromFormat("Y-m-d", "2026-05-23");
time();

SQL date functions

Syntax varies by engine. Examples for MySQL/MariaDB; PostgreSQL uses TO_CHAR ; SQLite uses strftime .

-- MySQL
SELECT NOW();
SELECT DATE_FORMAT(NOW(), '%Y-%m-%d %H:%i:%s');
SELECT UNIX_TIMESTAMP(NOW());

-- PostgreSQL
SELECT TO_CHAR(NOW(), 'YYYY-MM-DD HH24:MI:SS');

-- SQLite
SELECT strftime('%Y-%m-%d %H:%M:%S', 'now', 'localtime');