Date and Time Manager for Unix Timestamps

A single-header C++11 library for parsing, formatting, and managing Unix timestamps-including negative values (dates before 1970).

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Features

• Handles both positive and negative Unix timestamps (dates before and after 1970)
• Customizable date/time formatting
  Choose order (MDY, DMY, YMD), delimiter, show/hide day of week, time, UTC offset, use 12/24-hour time, month as number or name, and zero-padding
• Timezone offset support
• Operator overloading for date comparison and arithmetic
• Zero dependencies beyond the C++11 standard library

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Quick Start

1. Include the Header

#include "datepp.hpp"

2. Create and Use a DateTime

#include 
#include "datepp.hpp"

int main() {
    beliumgl::DateTime d("1700000000"); // Unix timestamp as string
    std::cout << d.toString() << std::endl; // Default format
}

3. Custom Formatting

beliumgl::DateTimeFormat fmt("W, DD.MM.YYYY HH:II:SS O UTC");
std::cout << dt.toString(fmt) << std::endl;

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How Does the String Format Work?

• Case-insensitive: You can use upper or lower case letters; it doesn't matter.
• Unknown characters are ignored (except when used as delimiters).
• Delimiter: The delimiter will be the last character separating D, M (or A), and Y in your format string.

Tokens

The format string uses the following tokens:

Token	Meaning	Note
W	Day of the week	Use WW for full names
D	Day	Use DD for zero-padded day
M	Month (number)	Use MM for zero-padded month
Y	Year	Use YY for zero-padded year
H	Hour
I	Minute	'I' is used because 'M' is for month
S	Second
O	UTC offset
_	12-hour format
A	Alphabetical month

Special Patterns

• WW - Show the full name of the day of the week (e.g., "Thursday").

• DD, MM, YY - Fill with zeros (e.g., "01", "09", "05").

• Single token (e.g., D, M, Y) - Short names or no leading zeros.

• NOTES: If there are at least one DD or MM or HH, etc., then date and time will also be filled with zeros. If any of H, I, or S is specified, the resulting string will still include all hours, minutes, and seconds.

Format Order

• The order of D, M (or A), and Y is important!
  • For example, MM/DD/YY and DD/MM/YY will be interpreted differently.

Optional Tokens

• H, I, S, W, O, _, and A are not required in the format.
• Omitting them will result in the loss of some information (e.g., time, UTC offset, time format, etc.).

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Example format:
"W, DD/MM/YY, HH:II:SS O"

• This would display something like: Thu, 01/01/1970, 00:00:00 +00 UTC

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API Overview

DateTimeFormat

• Customize how dates are displayed
• Example:

  beliumgl::DateTimeFormat fmt("DD.MM.YYYY");

DateTime

• Construct from Unix timestamp (string or char*)
• Convert to string in your chosen format
• Get individual components: year, month, day, hour, minute, second, day of week, UTC offset
• Operator overloads: compare, add, subtract, multiply, divide dates

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Example Usage

beliumgl::DateTime d("1700000000", 2.0); // timestamp, UTC+2
std::cout << d.toString("W, DD/MM/YY HH:II:SS O UTC") << std::endl;

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Notes

• Month and day are zero-based internally (January = 0, first day = 0), but formatted output is 1-based.

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