Covert to nfa

Convert regular expression to nfa

# include <stdio.h>

#include <conio.h>

#include <string.h>

#include <ctype.h>

int ret[100];

static int pos = 0;

static int sc = 0;

void nfa(int st, int p, char*s)

{

int i,sp,fs[15],fsc=0;

sp=st:pos=p;sc=st;

while(*s!=NULL)

{

if(isalpha(*s))

{ret[pos++]=sp;

ret[pos++]=*s;

ret[pos++]=++sc;}

if(*s=='.')

{

sp=sc;

ret[pos++]=sc;

ret[pos++]=238;

ret[pos++]=++sc;

sp=sc;}

if(*s=='|')

{sp=st;

fs[fsc++]=sc;}

if(*s=='*')

{ret[pos++]=sc;

ret[pos++]=238;

ret[pos++]=sp;

ret[pos++]=sp;

ret[pos++]=238;

ret[pos++]=sc;

}

if(*s=='(')

{

char ps[50];

int i=0,flag=1;

s++;

while(flag!=0)

{

ps[i++]=*s;

if(*s=='(')

flag++;

if(*s==')')

flag--;

s++;}

ps[--i]='\0';

nfa(sc,pos,ps);

s--;

}

s++;

}

sc++;

for(i=0;i<fsc;i++)

{

ret[pos++]=fs[i];

ret[pos++]=238;

ret[pos++]=sc;

}

ret[pos++]=sc-1;

ret[pos++]=238;

ret[pos++]=sc;

}

void main()

{

int i;

char *inp;

clrscr();

printf("enter the regular expression :");

gets(inp);

nfa(1,0,inp);

printf("\nstate intput state\n");

for(i=0;i<pos;i=i+3)

print("%d  --%c--> %d\n", ret[i], ret[i+1,ret[i+2]);

printf("\n");

getch();
}