//string3.cpp
//methods for class String implemented with overloaded operators

#include "string3.h"
#include <iostream.h>
#include <string.h>
#include <assert.h>

const int Max = 256;

//default constructor
String::String() {
	length = 0;
	val = new char;
	assert(val);
	*val = '\0';
}

//conversion constructor from a C string
String::String(const char *s) {
	length = strlen(s);
	val = new char[length+1];
	assert(val);
	strcpy(val, s);
}

//copy constructor
String::String(const String& s) {
	length = s.length;
	val = new char[length+1];
	assert(val);
	strcpy(val, s.val);
}

//destructor
String::~String() {
	delete [] val;
}

//returns the lenght of string
int String::getlength() {
	return length;
}

//assignment operator
String& String::operator=(const String& s) {

	if (this != &s) {
		delete [] val;
		length = s.length;
		val = new char[length+1];
		assert(val);
		strcpy(val, s.val);
	}
	return *this;
}

//concatenation operator: concatenates two strings
String& String::operator+=(const String& s) {

	length += s.length;
	char *temp = new char[length+1];
	assert(temp);
	strcpy(temp, val);
	strcat(temp, s.val);
	delete [] val;
	val = temp;
	return *this;
}

//concatenates two Strings, leaving both of them unchanged
String String::operator+(const String& s) {

	String result = *this;
	result += s;
	return result;
}

//equality operator: returns 1 if two strings are equal,
//otherwise returns 0
int String::operator==(const String& s) {
	if (length != s.length)
		return 0;
	return strcmp(val, s.val) == 0;
}

//subscript operator: returns pointer to nth element of string,
//if n is outside the length of string, returns NULL
char* String::operator[](int n) {
	if (n > length-1 || n < 0)
		return NULL;
	return &val[n];
}

//output operator: prints out string
ostream& operator <<(ostream& os, String& s) {
	return os<<s.val;
}

//input operator: reads in string from stdin, if line is longer
//than Max-1 characters, it is truncated
istream& operator >>(istream& is, String& s) {
	char temp[Max], ch;

	is.get(temp, Max);
		for(;;)
			if (!is.get(ch) || ch == '\n')
				break;
	s.length = strlen(temp);
	s.val = new char[s.length+1];
	assert(s.val);
	strcpy(s.val, temp);
	return is;
}