C program to find nCr and nPr (Combinations and Permutations)

on 04 September 2013

This is a C language program code to find nCr (Combinations) and nPr (Permutations). Note that the program uses following formulas to find nCr and nPr.

The permutations formula is (P(n,r) = n! / (n - r)!). The combinations formula is (C(n,r) = n! / r! (n - r)!). The exclamation mark in the formula suggests factorial. To avoid repetitiveness, we are using a function to calculate factorial.

/* Program to calculate nCr and nPr by reading values of n and r from user*/
#include <stdio.h>
#include <conio.h>
long int factorial (int x);

int main ()
    int n,r;
    long int ncr,npr;
    printf ("Enter value of n:");
    scanf ("%ld",&n);
    printf ("Enter value of r:");
    scanf ("%ld",&r);
    npr = factorial(n)/factorial(n-r);
    ncr = npr / factorial(r);
    printf ("npr value is:%ld\n",npr);
    printf ("ncr value is:%ld\n",ncr);
    getch ();
    return 0;

/* Function to calculate factorial */
long int factorial (int x)
    int i,f=1;
    for (i=2 ; i<=x ; i++)
        f = f * i;
    return (f);


C Program for nCr and nPr

Note: I have used FireCMD shell to compile the program.


Anonymous said...

Ps how do I write c programme for negative binomia

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