string-implementation-cpp

This project demonstrates a complete implementation of a String class in C++, mimicking the behavior of std::string while giving full control over memory management, object semantics, and operator overloading. It is a hands-on demonstration of deep knowledge in object-oriented programming, RAII, and STL-like usability.

Design

✨ Features

• Supports various construction styles:

  String s1;
  String s2("Ranjan Kumar");
  String s3 = "Ranjan Kumar";
  String s4 = s3;  // Deep copy
  s3[0] = 'y';     // Index operator overload
  
  

• Stream input/output support:

  cin >> s4;
  cout << s4 << endl;

• Fully overloaded comparison operators: ==, !=, <, <=, >, >=

• Robust concatenation logic (8 use-cases covered):

  String s = "Hello" + s2 + " Again" + '!';

• STL-style iterators: begin(), end()

• Move semantics: Move constructor and move assignment

• Dynamic memory management with deep copy support

• Length synchronization per object instance

🔧 Implementation Highlights

Member Functions

// Constructors and Destructor
String();                         // Default
String(const char* p);            // Parameterized
String(String&& other);           // Move
String(String& other);            // Deep Copy
~String();                        // Destructor

// Core Methods
void getstr();
int len();
char* begin();
char* end();

// Assignment Overloads
String& operator=(String& s2);
String& operator=(const char* ptr);
String& operator=(String&& other);

// Concatenation Overloads
String operator+(String&);
String& operator+=(String&);
String operator+(const char*);
String& operator+=(const char*);
String operator+(const char);
String& operator+=(const char);

// Access and Comparison
char& operator[](int i);
bool operator>(String& s2);
bool operator<(String& s2);
bool operator>=(String& s2);
bool operator<=(String& s2);
bool operator!=(String& s2);
bool operator==(String& s2);

Friend Functions

friend ostream& operator<<(ostream&, String&);
friend istream& operator>>(istream&, String&);

// Concatenation
friend String operator+(const char*, String&);
friend String operator+(const char, String&);

// Custom String Functions
friend unsigned int my_strlen(String&);
friend void my_strcpy(String&, String&);
friend void my_strncpy(String&, const String&, unsigned int);
friend int my_strcmp(const String&, const String&);
friend void my_strcat(String&, const String&);
friend void my_strncat(String&, const String&, unsigned int);
friend String& my_strrev1(String&);
friend void my_strrev2(String&, String&);
friend String& my_strupper(String&);
friend String& my_strlower(String&);
friend bool my_strchr(String&, char);
friend bool my_strrchr(String&, char);
friend bool my_strstr(const String&, const String&);

✅ Concatenation Support

Expression	Implementation Type	Status
s1 + s2	Member function	✅ Implemented
s1 += s2	Member function	✅ Implemented
s1 + "abc"	Member function	✅ Implemented
"abc" + s1	Friend function	✅ Implemented
s1 += "abc"	Member function	✅ Implemented
s1 + 'a'	Member function	✅ Implemented
'a' + s1	Friend function	✅ Implemented
s1 += 'a'	Member function	✅ Implemented

📌 Note: 'a' += s1 is invalid due to immutability of literals.

🧪 Performed Test Cases

Demonstrated in main.cpp:

/*** main.cpp ***/
int main() {

	String s1("vector india");
	s1[0] = 's';
	cout << "s1 = ";
	s1.getstr();
	
	cout<<"-------------------------------------------"<<endl;
	String s2 = "bangalore";
	cout<<"s2  = "<<s2<<endl;
	cout << "Length of s2 = " << s2.len() << endl;

	// Concatenation: Case 1
	cout<<"-------------------------------------------"<<endl;
	String s3;
	s3 = s1 + s2;
	cout<<"s1 = "<<s1<<", s2 = "<<s2<<endl;
	cout << "s3 = s1+s2 => ";
	s3.getstr();

	// Case 2
	cout<<"-------------------------------------------"<<endl;
	cout<<"s3 = "<<s3<<", s1 = "<<s1<<endl; 
	s3 += s1;
	cout << "s3 += s1 => " << s3 << endl;

	// Case 3
	cout<<"-------------------------------------------"<<endl;
	cout << "s1 = " << s1 << endl;
	s3 = s1 + "vector";
	cout<<" s3 = s1 + \"vector\" => "<<s3<<endl;

	// Case 4:
	cout<<"-------------------------------------------"<<endl;
	cout<<"s1 = "<<s1<<endl;
	s3 = "vector" + s1;
	cout << "s3 = \"vector\" + s1 => " << s3 << endl;

	// Case 5
	cout<<"-------------------------------------------"<<endl;
	cout<<"s3 = "<<s3<<endl;
	cout << "s3 += \"Vector\" => ";
	s3 += "Vector";
	cout <<s3 << endl;

	// Case 6
	cout<<"-------------------------------------------"<<endl;
	cout<<"s1 = "<<s1<<endl;
	s3 = s1 + 'x';
	cout << "s3 = s1 + 'x' => " << s3 << endl;

	// Case 7
	cout<<"-------------------------------------------"<<endl;
	cout<<"s1 = "<<s1<<endl;
	s3 = 'x' + s1;
	cout << "'x' + s1 = " << s3 << endl;

	// Case 8
	cout<<"-------------------------------------------"<<endl;
	cout<<"s3 = "<<s3<<endl;
	s3 += 'x';
	cout << "s3 += 'x' = " << s3 << endl;
	cout << "Length of s3 = " << s3.len() << endl;

	// [] and << overload
	cout<<"-------------------------------------------"<<endl;
	cout << "Characters of s3: ";
	for (int i = 0; i < s3.len(); i++) {
		cout << s3[i] << " ";
	}
	cout << endl;
	
	// >> overload and chaining support
	cout<<"-------------------------------------------"<<endl;
	String s4, s5;
	cout << "Enter two strings (s4 and s5): ";
	cin >> s4 >> s5;

	cout << "S4: " << s4 << endl;
	cout << "Length of s4 = " << s4.len() << endl;

	cout<<"-------------------------------------------"<<endl;
	cout << "s5 = ";
	s5.getstr();
	cout << "Length of s5 = " << s5.len() << endl;
	cout<<"--------------------------------------------"<<endl;
	
	// comparison operator
	cout<<"*********** String Comparision *************"<<endl;
	cout<<"--------------------------------------------"<<endl;
	cout<<"s4 = "<<s4<<endl;
	cout<<"s5 = "<<s5<<endl;
	cout<<"s4 >  s5 => "<< (s4>s5) << endl;
	cout<<"s4 >= s5 => "<< (s4>=s5) << endl;
	cout<<"s4 <  s5 => "<< (s4<s5) << endl;
	cout<<"s4 <= s5 => "<< (s4<=s5) << endl;
	cout<<"s4 == s5 => "<< (s4==s5) << endl;
	cout<<"s4 != s5 => "<< (s4!=s5) << endl;
	cout<<"--------------------------------------------"<<endl;

	return 0;
}

🛠️ Technologies Used

• C++
• GNU Make
• Valgrind (memory leak checks)
• Vi editor (development environment)

📁 Project Structure

.
├── String.hpp / String.cpp    # Class declaration and definition
├── main.cpp                   # Test cases for all features
└── Makefile                   # Build automation

📸 Output Snippet

s1 = sector india
s2 = bangalore
Length of s2 = 9
s3 = s1 + s2 => sector indiabangalore
s3 += s1 => sector indiabangaloresector india
s3 = s1 + "vector" => sector indiavector
s3 = "vector" + s1 => vectorsector india
s3 += "Vector" => vectorsector indiaVector
s3 = s1 + 'x' => sector indiax
s3 = 'x' + s1 => xsector india
s3 += 'x' => xsector indiax
...

---

This project showcases a deep understanding of C++ internals and strong command over modern object-oriented principles. Ideal for roles involving low-level system programming, high-performance applications, or custom STL-style library design.

---