Start of | Date String | Timestamp |
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A timestamp is a sequence of characters or encoded information that identifies when a certain event occurred. It usually includes the date and time of day, and can be accurate to a small fraction of a second. Timestamps don't have to be based on absolute time - they can be relative to any arbitrary time, such as system boot time.
There are three main types of time-related stamps: - Datestamp (DS): Shows only the date (e.g., 2024-11-15) - Timestamp (TS): Shows only the time of day (e.g., 20:07:20) - Date-timestamp (DTS): Shows both date and time (e.g., 2024-11-15, 20:07:20)
In computing, timestamps are used in various ways: - File systems: Recording when files were created, modified, or accessed - Digital cameras: Recording when pictures were taken - Logging systems: Recording when events occurred - Version control: Tracking when changes were made - Database systems: Managing data chronology and synchronization
ISO 8601 is the international standard for representing dates and times. Some common formats include: - 2024-11-15T20:07:20Z (ISO 8601) - 2024-11-15 20:07:20 (Common format) - 1256953732 (Unix timestamp) The 'Z' suffix indicates UTC timezone.
A Unix timestamp represents the number of seconds that have elapsed since January 1, 1970, at 00:00:00 UTC (the Unix Epoch). It's widely used in computing because it's simple, unambiguous, and easy to work with programmatically.
Timestamps are crucial for: - Event sequencing and ordering - Data synchronization - Audit trails and logging - File management - Version control - Database transactions - Digital signatures and certificates
Yes, timestamps can be inaccurate due to various factors: - System clock errors - Timezone misconfigurations - Daylight saving time transitions - Network time synchronization issues - Manual date/time changes It's important to validate timestamps when accuracy is crucial.
Modern file systems typically store three types of timestamps for each file: - Access time (atime): When the file was last accessed - Modification time (mtime): When the file's content was last modified - Change time (ctime): When the file's metadata was last changed
How to get current Unix timestamp in different programming languages
Language | Code Example |
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Python | # Method 1: Using time import time timestamp = int(time.time()) # Method 2: Using datetime from datetime import datetime timestamp = int(datetime.now().timestamp()) |
JavaScript | // Method 1: Using Date.now() const timestamp = Math.floor(Date.now() / 1000); // Method 2: Using new Date() const timestamp = Math.floor(new Date().getTime() / 1000); |
Java | // Method 1: Using System long timestamp = System.currentTimeMillis() / 1000L; // Method 2: Using Instant long timestamp = Instant.now().getEpochSecond(); |
C++ | // Method 1: Using chrono (C++11 and later) #include <chrono> auto timestamp = std::chrono::system_clock::now().time_since_epoch() / std::chrono::seconds(1); // Method 2: Using time.h #include <time.h> time_t timestamp = time(nullptr); |
C | #include <time.h> time_t timestamp = time(NULL); // or time(0) |
Go | // Method 1: Unix timestamp timestamp := time.Now().Unix() // Method 2: UnixNano for higher precision timestampNano := time.Now().UnixNano() / 1e9 |
Rust | // Method 1: Using SystemTime use std::time::{SystemTime, UNIX_EPOCH}; let timestamp = SystemTime::now() .duration_since(UNIX_EPOCH) .unwrap() .as_secs(); // Method 2: Using time crate use time::OffsetDateTime; let timestamp = OffsetDateTime::now_utc().unix_timestamp(); |
PHP | // Method 1: Using time() $timestamp = time(); // Method 2: Using strtotime() $timestamp = strtotime('now'); // Method 3: Using DateTime $timestamp = (new DateTime())->getTimestamp(); |
C# | // Method 1: Using DateTimeOffset long timestamp = DateTimeOffset.UtcNow.ToUnixTimeSeconds(); // Method 2: Using DateTime long timestamp = ((DateTimeOffset)DateTime.UtcNow).ToUnixTimeSeconds(); |
Ruby | # Method 1: Using Time timestamp = Time.now.to_i # Method 2: Using DateTime require 'date' timestamp = DateTime.now.to_time.to_i |
Swift | // Method 1: Using Date let timestamp = Int(Date().timeIntervalSince1970) // Method 2: Using TimeInterval let timestamp = Int(Date.timeIntervalSinceReferenceDate + Date.timeIntervalBetween1970AndReferenceDate) |
Kotlin | // Method 1: Using System val timestamp = System.currentTimeMillis() / 1000L // Method 2: Using Instant import java.time.Instant val timestamp = Instant.now().epochSecond |
R | # Method 1: Using Sys.time() timestamp <- as.integer(Sys.time()) # Method 2: Using as.POSIXct timestamp <- as.integer(as.POSIXct(Sys.time())) |
MATLAB | % Method 1: Using posixtime timestamp = posixtime(datetime('now')); % Method 2: Using now timestamp = round((now - datenum('1970-01-01')) * 86400); |
Perl | # Method 1: Using time my $timestamp = time(); # Method 2: Using Time::HiRes for higher precision use Time::HiRes qw(time); my $timestamp = int(time()); |
Scala | // Method 1: Using System val timestamp = System.currentTimeMillis() / 1000L // Method 2: Using Instant import java.time.Instant val timestamp = Instant.now.getEpochSecond |
TypeScript | // Method 1: Using Date.now() const timestamp: number = Math.floor(Date.now() / 1000); // Method 2: Using new Date() const timestamp: number = Math.floor(new Date().getTime() / 1000); |
Dart | // Method 1: Using DateTime int timestamp = DateTime.now().millisecondsSinceEpoch ~/ 1000; // Method 2: Using DateTime.timestamp int timestamp = DateTime.timestamp().millisecondsSinceEpoch ~/ 1000; |
Lua | -- Method 1: Using os.time() local timestamp = os.time() -- Method 2: Using os.date local timestamp = os.date("*t") |
SQL | -- MySQL SELECT UNIX_TIMESTAMP(); -- PostgreSQL SELECT EXTRACT(EPOCH FROM CURRENT_TIMESTAMP)::INTEGER; -- SQLite SELECT strftime('%s', 'now'); -- SQL Server SELECT DATEDIFF(SECOND, '1970-01-01', GETUTCDATE()); |
Delphi | // Method 1: Using DateTimeToUnix timestamp := DateTimeToUnix(Now); // Method 2: Using TDateTime uses DateUtils; timestamp := DateTimeToUnix(TDateTime.Now); |
VB.NET | ' Method 1: Using DateTimeOffset Dim timestamp As Long = DateTimeOffset.UtcNow.ToUnixTimeSeconds() ' Method 2: Using DateTime Dim timestamp As Long = CLng((DateTime.UtcNow - New DateTime(1970, 1, 1)).TotalSeconds) |
Groovy | // Method 1: Using System def timestamp = System.currentTimeMillis() / 1000L // Method 2: Using Instant import java.time.Instant def timestamp = Instant.now().epochSecond |
Haskell | -- Method 1: Using getPOSIXTime import Data.Time.Clock.POSIX timestamp <- round <$> getPOSIXTime -- Method 2: Using UTCTime import Data.Time.Clock timestamp <- round . utcTimeToPOSIXSeconds <$> getCurrentTime |