FIRST

#include<stdio.h> 
#include<ctype.h> 
void FIRST(char[],char );
void addToResultSet(char[],char); 
int numOfProductions; 
char productionSet[10][10]; 
int main() 
{ 
 int i;
 char choice; 
 char c;
 char result[20]; 
 printf("How many number of productions ? :"); 
 scanf(" %d",&numOfProductions); 
 for(i=0;i<numOfProductions;i++)//read production string eg: E=E+T 
 { 
 printf("Enter productions Number %d : ",i+1); 
 scanf(" %s",productionSet[i]); 
 } 
 do 
 { 
 printf("\n Find the FIRST of :"); 
 scanf(" %c",&c); 
 FIRST(result,c); //Compute FIRST; Get Answer in 'result' array 
 printf("\n FIRST(%c)= { ",c); 
 for(i=0;result[i]!='\0';i++) 
 printf(" %c ",result[i]); //Display result 
 printf("}\n");
 printf("press 'y' to continue : "); 
 scanf(" %c",&choice); 
 } 
 while(choice=='y'||choice =='Y'); 
} 
/*
 *Function FIRST: 
 *Compute the elements in FIRST(c) and write them 
 *in Result Array. 
 */ 
void FIRST(char* Result,char c)
{ 
 int i,j,k; 
 char subResult[20]; 
 int foundEpsilon; 
 subResult[0]='\0'; 
 Result[0]='\0'; 
 //If X is terminal, FIRST(X) = {X}. 
 if(!(isupper(c))) 
 { 
 addToResultSet(Result,c); 
 return ; 
 } 
 //If X is non terminal 
 //Read each production 
 for(i=0;i<numOfProductions;i++) 
 { 
//Find production with X as LHS 
 if(productionSet[i][0]==c) 
 { 
//If X → ε is a production, then add ε to FIRST(X). 
 if(productionSet[i][2]=='$') addToResultSet(Result,'$'); 
 //If X is a non-terminal, and X → Y1 Y2 … Yk
 //is a production, then add a to FIRST(X) 
 //if for some i, a is in FIRST(Yi), 
 //and ε is in all of FIRST(Y1), …, FIRST(Yi-1). 
 else 
 { 
 j=2; 
 while(productionSet[i][j]!='\0') 
 { 
 foundEpsilon=0; 
 FIRST(subResult,productionSet[i][j]); 
 for(k=0;subResult[k]!='\0';k++) 
 addToResultSet(Result,subResult[k]); 
 for(k=0;subResult[k]!='\0';k++) 
 if(subResult[k]=='$') 
 { 
foundEpsilon=1; 
 break; 
 } 
 //No ε found, no need to check next element 
 if(!foundEpsilon) 
 break; 
 j++; 
 } 
 } 
 } 
} 
 return ; 
} 
void addToResultSet(char Result[],char val) 
{ 
 int k; 
 for(k=0 ;Result[k]!='\0';k++) 
 if(Result[k]==val) 
 return; 
 Result[k]=val; 
 Result[k+1]='\0'; 
}