Implement all of your member functions in the source file. You are not permitted to use any standard library functionality this includes both the C Standard Library and the C++ Standard Library.

class String { private: char* buffer; int size; public: // Initializes a string to be empty (i.e., its length will // be zero and toChars() will return ""). String(); // Initializes a string to contain the characters in the // given C-style string, which is assumed to be null-terminated. String(const char* chars); // Initializes a string to be a copy of an existing string, // meaning that it contains the same characters and has the // same length. String(const String& s); // Destroys a string, releasing any memory that is being // managed by this object. ~String() noexcept; // Assigns an existing string into this one, replacing the // contents of this string with a copy of the contents of // the other. String& operator=(const String& s); // append() modifies this string so that it contains all // of the characters it currently contains, followed by // all of the characters of s. void append(const String& s); // at() returns one of the characters in the string, given // a zero-based index (i.e., the index 0 is the first // character of the string). There are two variants of // this member function, so that it is possible to use // this to modify a string's characters, but only if // the string is not constant. // // If the given index is not the index of a character // within the string (e.g., if a string's length is // five, valid indices range from 0..4 inclusive), // this member function throws an OutOfBoundsException. char at(unsigned int index) const; char& at(unsigned int index); // clear() makes this string be empty. void clear(); // compareTo() compares the contents of this string to the // contents of another string lexicographically, returning // zero if they're exactly equal, a negative value if this // string is "less than" the other one lexicographically, // or a positive value if this string is "greater than" // the other one lexicographically. int compareTo(const String& s) const noexcept; // concatenate() returns a string that contains the // characters in this string followed by the characters // in s. String concatenate(const String& s) const; // contains() returns true if this string contains the // given substring somewhere (e.g., the string "Is Boo // happy today?" contains the substring "Boo"), or false // otherwise. bool contains(const String& substring) const noexcept; // equals() returns true if this string is equivalent to // the given string (i.e., they both have the same length // and contain the same sequence of characters). bool equals(const String& s) const noexcept; // find() returns the index where the given substring is // found within this string, or -1 if it's not found. int find(const String& substring) const noexcept; // isEmpty() returns true if this string is empty, or // false otherwise. bool isEmpty() const noexcept; // length() returns the number of characters in this string. unsigned int length() const noexcept; // substring() returns a substring of this substring, // containing the characters beginning at startIndex // and ending at (but not including) endIndex. For // example, in the string "Boo is happy today", // substring(7, 12) would return "happy". String substring(unsigned int startIndex, unsigned int endIndex) const; // toChars() returns a C-style string that is equivalent // (i.e., has the same length and contains the same // sequence of characters) as this string. Note that // the C-style string is not allocated by this member // function, so it is not necessary to deallocate it. const char* toChars() const noexcept; };