c++ visual studio 2019

Do not use #include

Help me fix my program. Was told that : Syntax missing << prototype in main? (Your program does not compile. You are trying to use <<, but it is not defined)

original question:

16. Modify the String class in the following ways:
    1. Our String class always deletes the old character buffer and allocates a new character buffer on assignment or in the copy constructor. This need not be done if the new value is shorter than the current value and hence would fit the existing buffer. Rewrite the String class to only allocate a new buffer when necessary
    2. Overload the compound += operator to perform concatenation of two String objects.
    3. Overload the + operator using the += operator.
    4. Add a member function compare (String) that returns -1 or 0 or 1 depending on whether the string is lexicographically less than, equal to, or greater than the argument.

Provide a test program to test your class.

string.h---------------------------------------------------------------

#ifndef STRING_H #define STRING_H

class String { public: String(); // Default constructor String(const char p[]); // Simple constructor String(const String& right); // Copy constructor ~String(); // Destructor String& operator=(const String& right); // Assignment operator String& operator+=(const String& right); int length() const; char& operator[](int index); char operator[](int index) const; int compare(const String& data);//compare function implemented String operator+=(String& right);//+= operator overloaded String operator+(String& right);//+ operator overloaded

private: char* buffer; int len; };

#endif

string.cpp------------------------------------------------------

#include "string.h" #include #include

using namespace std;

String::String() { len = 0; buffer = NULL; // No need to allocate array to hold zero characters }

String::String(const char p[]) { // Determine number of characters in string (strlen(p)) len = 0; while (p[len] != '\0') len++; // Allocate buffer array, remember to make space for NULL character buffer = new char[len + 1]; // Copy new characters (strcpy( buffer, p )) for (int i = 0; i < len; i++) buffer[i] = p[i]; buffer[len] = '\0'; }

String::String(const String& right) { len = right.length(); buffer = new char[len + 1]; for (int i = 0; i < len; i++) buffer[i] = right[i]; buffer[len] = '\0'; }

String::~String() { delete[] buffer; }

int String::length() const { return len; }

char& String::operator [] (int index) { assert((index >= 0) && (index < len)); return buffer[index]; }

char String::operator [] (int index) const { assert((index >= 0) && (index < len)); return buffer[index]; }

// + opearator is overloaded for concatenation using the += operator

String String::operator+(String& right) { return *this += right; }

//+= operator is overloaded for concatenation

String String::operator +=(String& s2) { int l1 = len; int l2 = s2.length(); char* temp = new char[len + 1]; for (int i = 0; i < len; i++) { temp[i] = buffer[i]; } temp[len] = '\0'; delete[] buffer; len = l1 + l2; buffer = new char[len + 1]; for (int i = 0; i < l1; i++) { buffer[i] = temp[i]; } for (int i = 0; i < l2; i++) { buffer[l1 + i] = s2[i]; }

buffer[len] = '\0';

return *this; }

// = operator is optimized for assignment and allocates new space only when the other string length is more than the current buffer

String& String::operator=(const String& right) { if (this != &right) { if (right.length() > len) { delete[] buffer; // Get rid of old buffer len = right.length(); buffer = new char[len + 1]; } len = right.length(); for (int i = 0; i < len; i++) buffer[i] = right[i]; buffer[len] = '\0'; } return *this; }

int String::compare(const String& data) { for (int i = 0; i < this->len && i < data.length(); i++) { if (((int)this->buffer[i]) > ((int)data[i])) { return 1; } else if (((int)this->buffer[i]) < ((int)data[i])) { return -1; } else { continue; } } if (this->len > data.length()) { return 1; } if (this->len < data.length()) { return -1; } return 0; }

ostream& operator << (ostream& out, const String& right) { int n = right.length(); for (int i = 0; i < n; i++) out << right[i]; return out; }

stringtest.cpp--------------------------------------------------------------------

#include #include #include "string.h"

using namespace std;

int main() //stringtest { String new_name; cout << new_name << endl; char letters[] = "Hello World"; String s(letters); cout << s << endl; String first("Harry"); cout << first << endl; String second(first); cout << second << endl; String third = String("Two"); // Also uses copy constructor cout << third << endl; String classmates[5] = { "Draco", "Cedric" }; for (int i = 0; i < 5; i++) cout << i << " " << classmates[i] << endl; String test = classmates[2]; cout << "test is " << test << endl; cout << test.length() << endl; String a("Hermoine"); String b("Dumbledore"); String c = a + b;//using the + operator for concatenation cout << c << endl; cout << b.compare(a) << endl; String d("The "); d += c;//using the += operator for concatenation cout << d << endl; }