follow.c

#include<stdio.h>
#include<string.h>
int nop,m=0,p,i=0,j=0;
char prod[10][10],res[10];
void FOLLOW(char c);
void first(char c);
void result(char);
void main()
{
int i;
int choice;
char c,ch;
printf("Enter the no.of productions: ");
scanf("%d", &nop);
printf("enter the production string like E=E+T\n");
for(i=0;i<nop;i++)
{
printf("Enter productions Number %d : ",i+1);
scanf(" %s",prod[i]);
}
do
{
m=0;
printf("Find FOLLOW of -->");
scanf(" %c",&c);
FOLLOW(c);
printf("FOLLOW(%c) = { ",c);
for(i=0;i<m;i++)
printf("%c ",res[i]);
printf(" }\n");
printf("Do you want to continue(Press 1 to continue....)?");
scanf("%d%c",&choice,&ch);
}
while(choice==1);
}
void FOLLOW(char c)
{
if(prod[0][0]==c)
result('$');
for(i=0;i<nop;i++)
{
for(j=2;j<strlen(prod[i]);j++)
{
if(prod[i][j]==c)
{
if(prod[i][j+1]!='\0')
first(prod[i][j+1]);
if(prod[i][j+1]=='\0'&&c!=prod[i][0])
FOLLOW(prod[i][0]);
}
}
}
}
void first(char c)
{
int k;
if(!(isupper(c)))
result(c);
for(k=0;k<nop;k++)
{
if(prod[k][0]==c)
{
if(prod[k][2]=='$')
FOLLOW(prod[i][0]);
else if(islower(prod[k][2]))
result(prod[k][2]);
else
first(prod[k][2]);
}
}
}
void result(char c)
{
int i;
for( i=0;i<=m;i++)
if(res[i]==c)
return;
res[m++]=c;
}




//Enter the no.of productions: 8
//enter the production string like E=E+T
//Enter productions Number 1 : E=TX
//Enter productions Number 2 : X=+TX
//Enter productions Number 3 : X=$
//Enter productions Number 4 : T=FY
//Enter productions Number 5 : Y=*FY
//Enter productions Number 6 : Y=$
//Enter productions Number 7 : F=(E)
//Enter productions Number 8 : F=i
//Find FOLLOW of -->X