Program to find leading terminals:
#include<iostream.h>
#include<iostream.h>
#include<stdio.h>
#include<conio.h>
#include<string.h>
void install(char
x,char y);
void pop();
int pon(char u);
int pot(char v);
int checkstatus(int
a,int b);
int
n,d,f,xn,xt,top=-1;
char X,Y;
int a[20][20];
char
terminal[20],nonterm[20];
struct production
{
char l;
char r[10];
};
struct stack
{
char nt;
char t;
};
struct stack st[20];
struct production
prod[20];
void main()
{
clrscr();
cout<<"Provide
the number of terminals: ";
cin>>d;
cout<<"Provide
the terminal symbols for your production: ";
for(int
k=0;k<d;k++)
{
cin>>terminal[k];
}
cout<<"\n
Provide the number of non-terminals: ";
cin>>f;
cout<<"Provide
the non-terminal symbols for your production:";
for(k=0;k<f;k++)
{
cin>>nonterm[k];
}
cout<<
"\nHow many productions you want to Provide?? ";
cin>>n;
for(int
i=0;i<=n-1;i++)
{
cout<<"Provide
the "<< i+1<<" production: ";
cin>>prod[i].l;
cout<<"->";
cin>>prod[i].r;
}
for(int
p=0;p<f;p++)
{
for(int q=0;q<d;q++)
{
a[p][q]=0;
}
}
for(i=0;i<=n-1;i++)
{
for(int j=0;j<d;j++)
{
if(prod[i].r[0]==terminal[j])
install(prod[i].l,prod[i].r[0]);
else
if(prod[i].r[1]==terminal[j])
install(prod[i].l,prod[i].r[1]);
}
}
while(top>-1)
{
pop();
for(int
c=0;c<=n-1;c++)
{
if(prod[c].r[0]==X)
install(prod[c].l,Y);
}
}
//Output
cout<<"\n\n----------------------------------------------------------------";
cout<<"\n leading elements are:- " ;
cout<<"\n\n-----------------------------------------------------------------";
cout<<endl<<"
";
for(int
w=0;w<d;w++)
cout<<"
"<<terminal[w];
cout<<endl;
for(p=0;p<f;p++)
{
cout<<nonterm[p]<<"
";
for(int
q=0;q<d;q++)
{
cout<<a[p][q]<<"
";
}
cout<<endl;
}
getch();
}
void install(char
x,char y)
{
int g;
xn=pon(x);
xt=pot(y);
g=checkstatus(xn,xt);
if(g==0)
return;
else if(g==1)
{
top++;
st[top].nt=x;
st[top].t=y;
a[xn][xt]=1;
}
}
void pop()
{
X=st[top].nt;
Y=st[top].t;
top--;
}
int pon(char u)
{
for(int
x=0;x<f;x++)
{
if(u==nonterm[x])
return x;
}
}
int pot(char v)
{
for(int
x=0;x<d;x++)
{
if(v==terminal[x])
return x;
}
}
int checkstatus(int xn,int xt)
{
if(a[xn][xt]==1)
return 0;
else
return 1;
}
1 Comments
nice
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