C program to calculate nPr permutation and nCr combination.

#include<stdio.h>

#include<conio.h>

void main(){

long int n,i,r,factn=1,factr=1,factnr=1,npr,ncr;

clrscr();

printf("Enter positive integer value of n\n");

scanf("%ld",&n);

printf("Enter positive integer value of r\n");

scanf("%ld",&r);

if (n>r){

{

for (i=1;i<=n;++i)

factn=factn*i;

}

if (r>0){

for (i=1;i<=r;++i)

factr=factr*i;

}

if (n-r>0){

for (i=1;i<=n-r;++i)

factnr=factnr*i;

}

npr=factn/factnr;

ncr=npr/factr;

printf("ncr value = %ld and npr value = %ld",ncr,npr);

}

else {

printf("value of r(%ld) is greater than value of n(%ld)\n please try again",r,n);

}

getch();

}