C++ Program to Implement String Matching Using Vectors

«
»
This C++ program implements string matching using vectors. A text and a pattern is given as input. The pattern is searched for in the text and all instances of the pattern are given as output.

This C++ program is successfully compiled and tested on our system. The program output is given below.

  1. /*
  2.  * C++ Program to Implement String Matching Using Vectors
  3.  */
  4. #include<iostream>
  5. #include<string.h>
  6. #include<vector>
  7. using namespace std;
  8.  
  9. void input_string(vector<char>& str)
  10. {
  11.     char a;
  12.     while (1)
  13.     {
  14.         a = getchar();
  15.         if (a == '\n')
  16.         break;
  17.         str.push_back(a);
  18.     }
  19.     return;
  20. }
  21.  
  22. void print_string(vector<char> strn)
  23. {
  24.     for (std::vector<char>::iterator it = strn.begin();it != strn.end();++it)
  25.     {
  26.         cout<<*it;
  27.     }
  28.     return;
  29. }
  30.  
  31. int match_string(vector<char>& original, vector<char> match)
  32. {
  33.     vector<char>::iterator p,q, r;
  34.     int i = 0;
  35.  
  36.     p = original. begin();
  37.     while (r <= match.end() && p <= original.end())
  38.     {
  39.         r = match.begin();
  40.         while (*p != *r && p < original.end())
  41.         {
  42.             p++;
  43.             i++;
  44.         }
  45.  
  46.         q = p;
  47.         while (*p == *r && r <= match.end() && p<=original.end())
  48.         {
  49.             p++; i++;
  50.             r++;
  51.         }
  52.  
  53.         if (r >= match.end())
  54.         {
  55.             original.erase(original.begin(), q + 1);
  56.             return (i - match.size() + 1);
  57.         }
  58.  
  59.         if (p >= original.end())
  60.         return 0;
  61.         p = ++q;
  62.     }
  63. }
  64.  
  65.  
  66. int main()
  67. {
  68.     std::vector<char> original,match;
  69.     int i,result,k=0,sum=0;
  70.  
  71.     cout<<"Enter String:";
  72.     input_string(original);
  73.     cout<<"Enter Search Pattern:";
  74.     input_string(match);
  75.  
  76.     if (match.size() > original.size())
  77.     {
  78.         cout<<"Error:Original string too small.";
  79.     }
  80.  
  81.     do
  82.     {
  83.         result = match_string(original, match);
  84.         sum += result;    //to store previous found position
  85.         if (result > 0)
  86.         {
  87.             k++;
  88.             cout<<"\nMatch found from Position = "<<sum;
  89.         }
  90.      } while (result > 0);   //loop to find all patterns
  91.  
  92.      if (k == 0)
  93.          cout<<"Error:Match Not Found";
  94.      return 0;
  95. }

advertisement
Output:
 
Enter String:all men went to apall mall
Enter Search Pattern:all
 
Match found from Position = 1
Match found from Position = 19
Match found from Position = 24

Sanfoundry Global Education & Learning Series – 1000 C++ Programs.

advertisement
If you wish to look at all C++ Programming examples, go to C++ Programs.

Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!
advertisement
advertisement
advertisement
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn