fandf.c

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
int n, m = 0, i = 0, j = 0;
char a[10][10], f[10];
void follow(char c);
void first(char c);
int main()
{
    int 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("\n\nEnter the elements whose first and 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;
    else {
        for (k = 0; k < n; k++) {
            if (a[k][0] == c) {
                if (a[k][2] == '$' || 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]);
            }
        }
    }
}