C programming language: Factorial program in c using recursion.

Example: 5!=5*4*3*2*1=120
---------------
#include<stdio.h>
#include<conio.h>

int factorial(int n)
{
if(n<0)
return 0;
else if(n<=1)
return 1;
else
return (n*factorial(n-1));
}
void main()
{
int fact,n;
printf("\nEnter number:");
scanf("%d",&n);
fact=factorial(n);
printf("\nFactorial of %d is :%d ",n,fact);
getch();
}

C programming language: Factorial program in c without using recursion.

Example: 5!=5*4*3*2*1=120
--------------
#include<stdio.h>
#include<conio.h>

int factorial(int n)
{
int f=1,i;
for(i=1;i<=n;i++)
{
f=f*i;
}
return f;
}
void main()
{
int fact,n;
printf("\nEnter number:");
scanf("%d",&n);
fact=factorial(n);
printf("\nFactorial of %d is :%d ",n,fact);
getch();
}

C programming language: write a C program to count number of digits of given integer.

#include<stdio.h>
#include<conio.h>
void main()
{
int count=0,rem,num,n;
printf("\nEnter Numbers: ");
scanf("%d",&num);
n=num;
while(num)
{
rem=num%10;
count=count+1;
num=num/10;
}
printf("\nIn %d Having %d Digits...",n,count);
getch();
}

C progamming language: C program to check whether given number is even number or odd odd number.

#include<stdio.h>
#include<conio.h>
void main()
{
int num;
printf("\n Enter Number to check Even or odd: ");

scanf("%d",&num);
if (num %2 == 0)
printf("\n %d Is An Even Number..! ",num);
else
printf("\n %d Is An odd Number..! ",num);
getch();
}

C programming language : Write a Menu-driven program using Switch-case in C to perform mathematics operations Adition,Subtraction,Multiplication and Division.

    Write a menu driven program to perform following operations in C:
       i) Addition
      ii) Subtraction
     iii) Multiplication and
     iv) Division.

#include<stdio.h>
#include<conio.h>
#include<process.h>
void main()
{
int optn,a,b;
float c;
printf("\n1.Add: ");
printf("\n2.Subtract: ");
printf("\n3.Multiply: ");
printf("\n4.Divide: ");
printf("\n5.Exit: ");
printf("\nWhat u want to do?: ");
scanf("%d",&optn);
switch(optn)
do
{
case 1: printf("\nEnter Numbers to Add: ");
scanf("%d %d",&a,&b);
c=a+b;
printf("Addition's Result Is= %f",c);
break;

case 2: printf("\nEnter Numbers to Subtract: ");
   scanf("%d %d",&a,&b);
c=a-b;
printf("Subtraction's Result Is= %f",c);
   break;

case 3: printf("\nEnter Numbers to Multiply: ");
   scanf("%d %d",&a,&b);
c=a*b;
printf("Multiplication's Result Is= %f",c);
break;

case 4: printf("\nEnter Numbers to Divide: ");
   scanf("%d %d",&a,&b);
c=a/b;
printf("Dividion's Result Is= %f",c);
break;

case 5: exit(0);
default :printf("\n Invalid option...");

}while(optn!=0);
getch();
}