CD/lab5.c at master · NavneetSahay/CD · GitHub

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#include<stdio.h>
#include<math.h>
#include<string.h>
#include<ctype.h>
#include<stdlib.h>

int n,m=0,p,i=0,j=0;
char a[10][10],f[10];
void follow(char c);
void first(char c);

int main()
{
	int i,z;
	char c,ch;
	printf("Enter the no of productions:\n");
	scanf("%d",&n);

	printf("Enter the productions:\n");
	for(i=0;i<n;i++)
		scanf("%s%c",a[i],&ch);
	do
	{
		m=0;
		printf("Enter the elemets whose fisrt & follow is to be found : ");
		scanf("%c",&c);
		first(c);
		printf("First(%c)={",c);
		for(i=0;i<m;i++)
		printf("%c",f[i]);
		printf("}\n");
		strcpy(f," ");
		m=0;
		follow(c);
		printf("Follow(%c)={",c);
		for(i=0;i<m;i++)
		printf("%c",f[i]);
		printf("}\n");
		printf("Continue(0/1)?");
		scanf("%d%c",&z,&ch);
	}while(z==1);

	return(0);
}


void first(char c)
{
	int k;
	if(!isupper(c))
		f[m++]=c;
	for(k=0;k<n;k++)
	{
		if(a[k][0]==c)
		{
			if(a[k][2]=='$')
			follow(a[k][0]);
			else if(islower(a[k][2]))
			f[m++]=a[k][2];
			else first(a[k][2]);
		}
	}
}


void follow(char c)
{
	if(a[0][0]==c)
		f[m++]='$';
	for(i=0;i<n;i++)
	{
		for(j=2;j<strlen(a[i]);j++)
		{
			if(a[i][j]==c)
			{
				if(a[i][j+1]!='\0')
					first(a[i][j+1]);
				if(a[i][j+1]=='\0' && c!=a[i][0])
					follow(a[i][0]);
			}
		}
	}
}