The following source codes are used in this chapter. In C, we use the term string to refer to a variable-length array of characters, defined by a starting point and by a string-termination character marking the end. C++ inherits this data structure from C, also includes strings as a higher-level abstraction in the standard library.
// Data Structure & Algorithm C++, Otgonbayar Tovuudorj
// Chapter 15: Strings

// Naive search

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

// search first occurrence only and return its address
char *naivesearch1(char *pat, char *text) {
  register char *bp, *sp;
  
  if (*pat)
  while (*text) {
    bp = text; sp = pat;  
    do {
      if (!*sp) return text;
      else if(!*bp) return 0;
    } while (*bp++ == *sp++);
    text++;
  }
  return 0;
}


// search first occurrence only and return it location
int naivesearch(char *pat, char *text) {
  int i, j, m = strlen(pat), n = strlen(text);
  for(i=0, j=0; j<m && i<n; i++, j++)
    if(text[i] != pat[j]) { i -= j; j = -1; }
  if ((j==m) && m) 
    return i-m+1; 
  else 
    return 0;
}

// search all occurrences and prints their locations
void naivesearchall(char *pat, char *text) {
  int i, j, m = strlen(pat), n = strlen(text);
  for(i=0, j=0; j<=m && i<=n; i++, j++)
    if((text[i] != pat[j]) || ( !text[i] && !pat[j])) { 
      if ((j == m) && m) 
	    cout << " found at location: "<< i-m+1 << endl;  
      i -= j; 
      j = -1;
    }
}

int main() {
  char s[] = "This is most simple searching algorithm";
  char s1[40];
  
  cout << "Text: " << s << endl;
  cout << "string to be searched: ";  gets(s1);
  
  naivesearchall(s1, s);
  
  cout << naivesearch(s1, s) << endl; 
  cout << naivesearch1(s1, s) << endl;
}

// Data Structure & Algorithm C++, Otgonbayar Tovuudorj
// Chapter 15: Strings

// KMP search

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

void initnext(char *pat, int next[], int m) {
  int i, j;
  next[0] = -1;
  for(i=0, j= -1; i<m; i++, j++, next[i] = j)
    while((j>=0) && (pat[i] != pat[j])) 
	  j = next[j];
}

int kmpsearch(char *pat, char *text) {
  int i, j, m = strlen(pat), n = strlen(text);
  int *next = new int[m];
  if(*pat) {
    initnext(pat, next, m);
    for(i=0, j=0; j<m && i<n; i++, j++)
      while((j>=0) && (text[i] != pat[j])) 
	    j = next[j];
    if(j == m) 
	  return i-m+1; 
	else 
	  return 0;
  }
  return 0;
}

int main(void)
{
  char text[] = "111111100111010010100010100111000111";
  char p[40];
  int res;
  
  cout << "Text: " << text << endl;
  cout << "Input string: "; gets(p);
  
  res = kmpsearch(p, text);
  
  cout << res << endl;
}

// Data Structure & Algorithm C++, Otgonbayar Tovuudorj
// Chapter 15: Strings

// Boyer-Moore search

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

#define max(A, B) (A > B) ? A : B;
int pos[256];

void initpos(char *pat) {
  int j, M = strlen(pat);
  for (j = 0; j < 256; j++) pos[j] = M;
  for (j = 0; j < M; j++) pos[pat[j]] = M-j-1;
}

int bmsearch(char *pat, char *text) {
  int i, j;
  int M = strlen(pat), N = strlen(text);
  initpos(pat);
  for (i = M-1, j = M-1; j >= 0; i--, j--)
    while (text[i] != pat[j]) {
      i += max(M-j, pos[text[i]]);
      if (i >= N) return 0;    // not found
      j = M-1;
    }
  return i+2;                // at location: i+2
}

int main() {
  char text[] = "this is a searching examples for boyer moore algorithm&";
  char pat[50];
  int loc;
  
  cout << text << " - "<< strlen(text) << endl;
  cout << "Input string: "; gets(pat);
  
  if (loc = bmsearch(pat, text)) 
    cout << "Found at location: " << loc <<endl;
  else
    cout << "Not found" << endl;
}