Converting dfa / regular expression to C Program step wise explanation | deterministic finite automata

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Given : Regular Expression ((0 +1)* 01)

Step 1 
Langugage L = {01,001,101,1101,000101, 001101 }
Minimum strings = { 01,001,101}
Few examples of invalid strings ={ 000,11100,01010}

Step 2
Draw Dfa of given regular expression 
or draw Nfa of given regular expression  and convert it to Dfa


Dfa of (( 0+1)*01)

dead states =  null 
initial state = State 1
Final State = state 3


Step 3
construct transition table of Dfa



Step 4
C program implementation


#include <stdio.h>
#include <string.h>
#include<conio.h>

int main()
{
char s[20];
int l, State, c;
char Temp;


   printf("\n enter string to check: \n");
   gets(s);
  l=strlen(s);                                                                   //length of the string 
   printf("String length is %d \n", l);


c=0;
printf("count  is %d \n", c);

State=1;                                                                    // initial state
printf("State is %d \n", State);


      while(c<l)
{
Temp=s[c];

switch(State)
{
case 1:    
if(Temp=='0')
State=2;

if(Temp=='1')
State=1;
break;

case 2:  
if(Temp=='0')
State=2;
if(Temp=='1')
State=3;
break;

case 3:  
if(Temp=='0')
State=2;
if(Temp=='1')
State=1;
break;
}
c++;
}

   if(State==3)
printf("Valid string \n");
else
printf("InValid string \n");
   
      getch();
      return 0;
}

Step 5 
output




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Converting dfa / regular expression to C Program step wise explanation | deterministic finite automata