A set class for characters
/*
Quote from: C++: A Beginner"s Guide, Second Edition
# Publisher: McGraw-Hill Osborne Media; 2 edition (December 3, 2003)
# Language: English
# ISBN-10: 0072232153
# ISBN-13: 978-0072232158
*/
#include <iostream>
using namespace std;
const int MaxSize = 100;
class Set {
int len; // number of members
char members[MaxSize]; // this array holds the set
/* The find() function is private because it
is not used outside the Set class. */
int find(char ch); // find an element
public:
// Construct a null set.
Set() { len = 0; }
// Return the number of elements in the set.
int getLength() { return len; }
void showset(); // display the set
bool isMember(char ch); // check for membership
Set operator +(char ch); // add an element
Set operator -(char ch); // remove an element
Set operator +(Set ob2); // set union
Set operator -(Set ob2); // set difference
};
/* Return the index of the element
specified by ch, or -1 if not found. */
int Set::find(char ch) {
int i;
for(i=0; i < len; i++)
if(members[i] == ch) return i;
return -1;
}
// Show the set.
void Set::showset() {
cout << "{ ";
for(int i=0; i<len; i++)
cout << members[i] << " ";
cout << "}\n";
}
/* Return true if ch is a member of the set.
Return false otherwise. */
bool Set::isMember(char ch) {
if(find(ch) != -1) return true;
return false;
}
// Add a unique element to a set.
Set Set::operator +(char ch) {
Set newset;
if(len == MaxSize) {
cout << "Set is full.\n";
return *this; // return existing set
}
newset = *this; // duplicate the existing set
// see if element already exists
if(find(ch) == -1) { // if not found, then add
// add new element to new set
newset.members[newset.len] = ch;
newset.len++;
}
return newset; // return updated set
}
// Remove an element from the set.
Set Set::operator -(char ch) {
Set newset;
int i = find(ch); // i will be -1 if element not found
// copy and compress the remaining elements
for(int j=0; j < len; j++)
if(j != i) newset = newset + members[j];
return newset;
}
// Set union.
Set Set::operator +(Set ob2) {
Set newset = *this; // copy the first set
// Add unique elements from second set.
for(int i=0; i < ob2.len; i++)
newset = newset + ob2.members[i];
return newset; // return updated set
}
// Set difference.
Set Set::operator -(Set ob2) {
Set newset = *this; // copy the first set
// Subtract elements from second set.
for(int i=0; i < ob2.len; i++)
newset = newset - ob2.members[i];
return newset; // return updated set
}
// Demonstrate the Set class.
int main() {
// construct 10-element empty Set
Set s1;
Set s2;
Set s3;
s1 = s1 + "A";
s1 = s1 + "B";
s1 = s1 + "C";
cout << "s1 after adding A B C: ";
s1.showset();
cout << "\n";
cout << "Testing for membership using isMember().\n";
if(s1.isMember("B"))
cout << "B is a member of s1.\n";
else
cout << "B is not a member of s1.\n";
if(s1.isMember("T"))
cout << "T is a member of s1.\n";
else
cout << "T is not a member of s1.\n";
cout << "\n";
s1 = s1 - "B";
cout << "s1 after s1 = s1 - "B": ";
s1.showset();
s1 = s1 - "A";
cout << "s1 after s1 = s1 - "A": ";
s1.showset();
s1 = s1 - "C";
cout << "s1 after a1 = s1 - "C": ";
s1.showset();
cout << "\n";
s1 = s1 + "A";
s1 = s1 + "B";
s1 = s1 + "C";
cout << "s1 after adding A B C: ";
s1.showset();
cout << "\n";
s2 = s2 + "A";
s2 = s2 + "X";
s2 = s2 + "W";
cout << "s2 after adding A X W: ";
s2.showset();
cout << "\n";
s3 = s1 + s2;
cout << "s3 after s3 = s1 + s2: ";
s3.showset();
s3 = s3 - s1;
cout << "s3 after s3 - s1: ";
s3.showset();
cout << "\n";
cout << "s2 after s2 = s2 - s2: ";
s2 = s2 - s2; // clear s2
s2.showset();
cout << "\n";
s2 = s2 + "C"; // add ABC in reverse order
s2 = s2 + "B";
s2 = s2 + "A";
cout << "s2 after adding C B A: ";
s2.showset();
return 0;
}s1 after adding A B C: { A B C }
Testing for membership using isMember().
B is a member of s1.
T is not a member of s1.
s1 after s1 = s1 - "B": { A C }
s1 after s1 = s1 - "A": { C }
s1 after a1 = s1 - "C": { }
s1 after adding A B C: { A B C }
s2 after adding A X W: { A X W }
s3 after s3 = s1 + s2: { A B C X W }
s3 after s3 - s1: { X W }
s2 after s2 = s2 - s2: { }
s2 after adding C B A: { C B A }
