Question

Write C++ program

Consider the following SimpleString class:

class simpleString

{

    public:

         simpleString( );                                 // Default constructor

         simpleString(int mVal );                    // Explicit value constructor

         ~simpleString() { delete [ ] s;}          // Destructor

void readString();                              // Read a simple string

         void writeString() const;                    // Display a simple string

char at(int pos) const;                       // Return character at (pos)

         int getLength() const;                        // Return the string length

         int getCapacity() const;                     // Return the string capacity

         void copyContents(char[ ]) const;     // Copy the contents into an array

   private:

         int capacity;                                      // maximum size

           char *s;                                             // pointer to a dynamic storage array

         int length;                                         // current length

};

Add to the above class the following two public member function:

1. A function eraseToEnd (p) to erase all characters starting from position (p) in the string to the end of the string.
2. A function findsub (SimpleString sub). The function should return the position of start of substring (sub) in the string. If (sub) does not exist in the string, the function returns -1

Hint:

Consider the problem of searching in a string of text T[0 .. n-1] for a substring that matches a pattern P[0..m-1]. A simple Brute Force algorithm is:

ALGORITHM StringMatch (T[0..n-1], P[0..m-1])

{

      for i = 0 to n-m

      {

         j = 0;

         while ( (j < m) AND (P[j] == T[i + j]) ) j++;

         if ( j == m) return i;

       }

            return -1;

}

Implement the function findsub (SimpleString sub) using the above algorithm.

Provide the implementation of the above two functions.

Answer 1

ANS:

#include<string>
#include<iostream>
using namespace std;

class simpleString
{
private:

   int capacity; // maximum size

   char* s; // pointer to a dynamic storage array

   int length; // current length

public:

   simpleString() // Default constructor
   {
       capacity = 10;
       s = new char[capacity];
       length = 0;
   }

   simpleString(int mVal) // Explicit value constructor
   {
       capacity = mVal;
       s = new char[mVal];
   }

   ~simpleString()
   { delete[] s; } // Destructor Deleting dynamic character array in the end of program

   void readString() // Read a simple string
   {
      
       cout << "Enter the string:" << endl;
       cin >> s;

       while (s[length] != '\0')
       {
           length = length + 1;

       }
      
   }

   void writeString() const // Display a simple string
   {
       cout << "Displaying the String" << endl << endl;
       for (int i = 0; i<=length; i++)
       {
           cout << s[i];
       }
   }

   char at(int pos) const // Return character at (pos)
   {
       if (pos < length && pos < capacity)
       {
           return s[pos];
       }
   }

   int getLength() const // Return the string length
   {
       cout << "Length:" << endl;
       return length;
   }

   int getCapacity() const // Return the string capacity
   {
       cout << "Capacity:" << endl;
       return capacity;
   }

   void copyContents(char a[]) const // Copy the contents into an array
   {
       cout << "Copying contents into an array" << endl;
       for (int i = 0; a[i] != '\0'; i++)
       {
           s[i] = a[i];
       }

   }

   void eraseToEnd(int p)
   {
       cout << "Erasing elements from p to the end" << endl;
       //entereing -1 means erasing and reducing length
       length = p;

       for (int i = p; s[i] != '\0'; i++)
       {
           s[i] = -1;
       }

   }

   int findSub(simpleString sub)
   {

       for (int i = 0; i < (length - sub.length); i++)
       {
           int j = 0;
           while (j < sub.length && (sub.s[j] == s[i + j]))
           {
               j++;
           }
           if (j == sub.length)
           {
               return i;
           }
       }

       return -1;
   }

};

int main()
{
   simpleString obj(20);
   obj.readString();
   cout <<"at 5th index "<< obj.at(5)<<endl;
   cout << "Length of string:" << obj.getLength() << endl;
   obj.writeString();
   obj.eraseToEnd(3);
   obj.writeString();

}

Comment down for any queries
Please give a thumbs up if you are satisfied with answer :)