Custom Date & String Library in C++

A custom C++ utility library that provides Date Manipulation and String Processing functionalities implemented from scratch using Object-Oriented Programming principles.

The project contains two main libraries:

• clsString → A utility class for string processing and text manipulation.
• clsDate → A utility class for date calculations, comparisons, calendars, and date arithmetic.

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Features

String Library (clsString)

• Count words in a string.
• Convert:
  • First letter of each word to uppercase/lowercase.
  • Entire string to uppercase/lowercase.
  • Invert letter cases.
• Count:
  • Capital letters.
  • Small letters.
  • Specific characters.
  • Vowels.
• Split strings using custom delimiters.
• Join strings.
• Trim spaces:
  • Left trim.
  • Right trim.
  • Full trim.
• Reverse words in a sentence.
• Replace words.
• Remove punctuation characters.

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Date Library (clsDate)

• Construct dates using:

  • Current system date.
  • String format (dd/mm/yyyy).
  • Day, Month, Year.
  • Day order inside a year.

• Leap year detection.

• Get:

  • Number of days in a month.
  • Number of days, hours, minutes, and seconds in a month or year.

• Convert dates to string format.

• Calculate:

  • Day order in a year.
  • Difference between two dates.
  • Age in days.

• Compare dates:

  • Equal.
  • Before.
  • After.

• Date arithmetic:

  • Add/Subtract:
    • Days
    • Weeks
    • Months
    • Years
    • Decades
    • Centuries
    • Millenniums

• Calendar utilities:

  • Print monthly calendar.
  • Print yearly calendar.

• Vacation calculations:

  • Business days count.
  • Vacation duration.
  • Return date after vacation.

• Validate dates.

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Project Structure

├── clsString.h
├── clsDate.h
├── String.cpp      // Examples of using clsString
└── Date.cpp        // Examples of using clsDate

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Example Usage

String Library

#include "clsString.h"

int main() {

    clsString S("hello world");

    S.UpperFirstLetterOfEachWord();

    cout << S.getValue();

    // Output:
    // Hello World

    return 0;
}

Count Words

cout << clsString::CountWords("I Love C++");

// Output:
// 3

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Date Library

#include "clsDate.h"

int main() {

    clsDate Date1(10, 5, 2026);

    Date1.IncreaseDateByXDays(20);

    cout << Date1.DateToString();

    return 0;
}

Difference Between Two Dates

clsDate Date1("1/1/2026");
clsDate Date2("10/1/2026");

cout << clsDate::CalculateDifferenceBetweenTwoDatesInDays(Date1, Date2);

// Output:
// 9

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OOP Concepts Used

• Classes and Objects
• Encapsulation
• Constructors Overloading
• Static Methods
• Method Overloading
• Enumerations (enum)
• Utility Library Design
• Date Algorithms
• String Processing Algorithms

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Purpose

The goal of this project is to build custom utility libraries similar to the built-in libraries available in modern programming languages, while practicing Object-Oriented Programming (OOP) and implementing the algorithms manually without relying on external libraries.

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What I Learned

Through this project, I practiced:

• Designing reusable utility libraries.

• Implementing date algorithms from scratch.

• Building custom string manipulation functions.

• Using static and member functions effectively.

• Applying OOP concepts in real-world style libraries.

• Working with vectors, strings, and time-related functions in C++.

  Future Improvements

• Add operator overloading for date comparison (==, <, >).

• Support multiple date formats.

• Add exception handling for invalid dates.

• Extend string utilities with regex support.