Deterministic Finite Automaton
A deterministic finite automaton (DFA) also known as deterministic finite state machine , is a finite state machine that accepts/rejects finite strings of symbols and only produces a unique computation (or run) of the automaton for each input string. Source: Wikipedia
Conversion to C/C++ or Java Code
we can easily convert any DFA to Code , here is the machine that will accept string that contain "nano" sub string and will reject all other strings
#include<iostream>
#include<conio.h>
using namespace std;
int main()
{
	string str ;
	cout<<"Enter String to Test: "<<endl;
	cin>>str;
	int state=1; // start state
	for(int i=0;i<str.length();i++)
	{
		char c = str[i];
		 switch (state) {
                case (1): {
                    if (c == 'n' || c == 'N') {
                        state = 2;
                    }
                }
                break;
                case (2): {
                    if (c == 'a' || c == 'A') {
                        state = 3;
                    } else if (c == 'n' || c == 'N') {
                        state = 2;
                    }
                }
                break;
                case (3): {
                    if (c == 'n' || c == 'N') {
                        state = 4;
                    } else {
                        state = 1;
                    }
                }
                break;
                case (4): {
                    if (c == 'o' || c == 'O') {
                        state = 5;
                    } else if (c == 'n' || c == 'N') {
                        state = 2;
                    } else {
                        state = 1;
                    }
                }
                break;
                case (5): {
                    state = 5;
                }
                break;
            }
        }
         if (state == 5) {
            cout<<"DFA Accepts this string"<<endl;
        } else {
           cout<<"DFA does not accepts this string"<<endl;
        }
        getch();
        return 0;

	}