C++ Program to Implement Bitap Algorithm for String Matching

#include <string>
#include <map>
#include <iostream>
 
using namespace std;
int bitap_search(string text, string pattern)
{
    int m = pattern.length();
    long pattern_mask[256];
    /** Initialize the bit array R **/
    long R = ~1;
    if (m == 0)
        return -1;
    if (m > 63)
    {
        cout<<"Pattern is too long!";
        return -1;
    }
 
    /** Initialize the pattern bitmasks **/
    for (int i = 0; i <= 255; ++i)
        pattern_mask[i] = ~0;
    for (int i = 0; i < m; ++i)
        pattern_mask[pattern[i]] &= ~(1L << i);
    for (int i = 0; i < text.length(); ++i)
    {
        /** Update the bit array **/
        R |= pattern_mask[text[i]];
        R <<= 1;
        if ((R & (1L << m)) == 0)
 
            return i - m + 1;
    }
    return -1;
}
void findPattern(string t, string p)
{
    int pos = bitap_search(t, p);
    if (pos == -1)
        cout << "\nNo Match\n";
    else
        cout << "\nPattern found at position : " << pos;
}
 
int main(int argc, char **argv)
{
 
    cout << "Bitap Algorithm Test\n";
    cout << "Enter Text\n";
    string text;
    cin >> text;
    cout << "Enter Pattern\n";
    string pattern;
    cin >> pattern;
    findPattern(text, pattern);
}

Output:

 
Bitap Algorithm Test
Enter Text
DharmendraHingu
Enter Pattern
Hingu
 
Pattern found at position : 10