C program to find hcf and lcm

C program to find hcf and lcm: The code below finds highest common factor and least common multiple of two integers. HCF is also known as greatest common divisor(GCD) or greatest common factor(gcf).

C programming code

#include <stdio.h>
 
int main() {
  int a, b, x, y, t, gcd, lcm;
 
  printf("Enter two integers\n");
  scanf("%d%d", &x, &y);
 
  a = x;
  b = y;
 
  while (b != 0) {
    t = b;
    b = a % b;
    a = t;
  }
 
  gcd = a;
  lcm = (x*y)/gcd;
 
  printf("Greatest common divisor of %d and %d = %d\n", x, y, gcd);
  printf("Least common multiple of %d and %d = %d\n", x, y, lcm);
 
  return 0;
}

Download HCF and LCM program.

Output of program:

C program to find hcf and lcm using recursion

#include <stdio.h>
 
long gcd(long, long);
 
int main() {
  long x, y, hcf, lcm;
 
  printf("Enter two integers\n");
  scanf("%ld%ld", &x, &y);
 
  hcf = gcd(x, y);
  lcm = (x*y)/hcf;
 
  printf("Greatest common divisor of %ld and %ld = %ld\n", x, y, hcf);
  printf("Least common multiple of %ld and %ld = %ld\n", x, y, lcm);
 
  return 0;
}
 
long gcd(long a, long b) {
  if (b == 0) {
    return a;
  }
  else {
    return gcd(b, a % b);
  }
}

C program to find hcf and lcm using function

#include <stdio.h>
 
long gcd(long, long);
 
int main() {
  long x, y, hcf, lcm;
 
  printf("Enter two integers\n");
  scanf("%ld%ld", &x, &y);
 
  hcf = gcd(x, y);
  lcm = (x*y)/hcf;
 
  printf("Greatest common divisor of %ld and %ld = %ld\n", x, y, hcf);
  printf("Least common multiple of %ld and %ld = %ld\n", x, y, lcm);
 
  return 0;
}
 
long gcd(long x, long y) {
  if (x == 0) {
    return y;
  }
 
  while (y != 0) {
    if (x > y) {
      x = x - y;
    }
    else {
      y = y - x;
    }
  }
 
  return x;
}

Add digits of number in c

C program to add digits of a number: Here we are using modulus operator(%) to extract individual digits of number and adding them.

C programming code

#include <stdio.h>
 
int main()
{
   int n, sum = 0, remainder;
 
   printf("Enter an integer\n");
   scanf("%d",&n);
 
   while(n != 0)
   {
      remainder = n % 10;
      sum = sum + remainder;
      n = n / 10;
   }
 
   printf("Sum of digits of entered number = %d\n",sum);
 
   return 0;
}

For example if the input is 98, sum(variable) is 0 initially
98%10 = 8 (% is modulus operator which gives us remainder when 98 is divided by 10).
sum = sum + remainder
so sum = 8 now.
98/10 = 9 because in c whenever we divide integer by another integer we get an integer.
9%10 = 9
sum = 8(previous value) + 9
sum = 17
9/10 = 0.
So finally n = 0, loop ends we get the required sum.

Download Add digits program.

Output of program:

Add digits using recursion

#include <stdio.h>
 
int add_digits(int);
 
int main() 
{
  int n, result;
 
  scanf("%d", &n);
 
  result = add_digits(n);
 
  printf("%d\n", result);
 
  return 0;
}
 
int add_digits(int n) {
  static int sum = 0;
 
  if (n == 0) {
    return 0;
  }
 
  sum = n%10 + add_digits(n/10);
 
  return sum;
}

Static variable sum is used and is initialized to 0, it' value will persists after function calls i.e. it is initialized only once when a first call to function is made.

C program to check leap year

C program to check leap year: c code to check leap year, year will be entered by the user.

C programming code

#include <stdio.h>
 
int main()
{
  int year;
 
  printf("Enter a year to check if it is a leap year\n");
  scanf("%d", &year);
 
  if ( year%400 == 0)
    printf("%d is a leap year.\n", year);
  else if ( year%100 == 0)
    printf("%d is not a leap year.\n", year);
  else if ( year%4 == 0 )
    printf("%d is a leap year.\n", year);
  else
    printf("%d is not a leap year.\n", year);  
 
  return 0;
}

Download Leap year program.

Output of program:

Please read the leap year article at Wikipedia, it will help you to understand the program. This code is based on Gregorian Calendar.

C program to check whether input alphabet is a vowel or not

This code checks whether an input alphabet is a vowel or not. Both lower-case and upper-case are checked.

C programming code

#include <stdio.h>
 
int main()
{
  char ch;
 
  printf("Enter a character\n");
  scanf("%c", &ch);
 
  if (ch == 'a' || ch == 'A' || ch == 'e' || ch == 'E' || ch == 'i' || ch == 'I' || ch =='o' || ch=='O' || ch == 'u' || ch == 'U')
    printf("%c is a vowel.\n", ch);
  else
    printf("%c is not a vowel.\n", ch);
 
  return 0;
}

Output of program:

Check vowel using switch statement

#include <stdio.h>
 
int main()
{
  char ch;
 
  printf("Input a character\n");
  scanf("%c", &ch);
 
  switch(ch)
  {
    case 'a':
    case 'A':
    case 'e':
    case 'E':
    case 'i':
    case 'I':
    case 'o':
    case 'O':
    case 'u':
    case 'U':
      printf("%c is a vowel.\n", ch);
      break;
    default:
      printf("%c is not a vowel.\n", ch);
  }              
 
  return 0;
}

Function to check vowel

int check_vowel(char a)
{
    if (a >= 'A' && a <= 'Z')
       a = a + 'a' - 'A';   /* Converting to lower case or use a = a + 32 */
 
    if (a == 'a' || a == 'e' || a == 'i' || a == 'o' || a == 'u')
       return 1;
 
    return 0;
}

This function can also be used to check if a character is a consonant or not, if it's not a vowel then it will be a consonant, but make sure that the character is an alphabet not a special character.

C program to perform addition, subtraction, multiplication and division

C program to perform basic arithmetic operations which are addition, subtraction, multiplication and division of two numbers. Numbers are assumed to be integers and will be entered by the user.

C programming code

#include <stdio.h>
 
int main()
{
   int first, second, add, subtract, multiply;
   float divide;
 
   printf("Enter two integers\n");
   scanf("%d%d", &first, &second);
 
   add        = first + second;
   subtract = first - second;
   multiply = first * second;
   divide     = first / (float)second;   //typecasting
 
   printf("Sum = %d\n",add);
   printf("Difference = %d\n",subtract);
   printf("Multiplication = %d\n",multiply);
   printf("Division = %.2f\n",divide);
 
   return 0;
}

Download Arithmetic operations program.

Output of program:

In c language when we divide two integers we get integer result for example 5/2 evaluates to 2. As a general rule integer/integer = integer and float/integer = float or integer/float = float. So we convert denominator to float in our program, you may also write float in numerator. This explicit conversion is known as typecasting.

c program to check odd or even

c program to check odd or even: We will determine whether a number is odd or even by using different methods all are provided with a code in c language. As you have study in mathematics that in decimal number system even numbers are divisible by 2 while odd are not so we may use modulus operator(%) which returns remainder, For example 4%3 gives 1 ( remainder when four is divided by three). Even numbers are of the form 2*p and odd are of the form (2*p+1) where p is is an integer.

C program to check odd or even using modulus operator

#include<stdio.h>
 
main()
{
   int n;
 
   printf("Enter an integer\n");
   scanf("%d",&n);
 
   if ( n%2 == 0 )
      printf("Even\n");
   else
      printf("Odd\n");
 
   return 0;
}

We can use bitwise AND (&) operator to check odd or even, as an example consider binary of 7 (0111) when we perform 7 & 1 the result will be one and you may observe that the least significant bit of every odd number is 1, so ( odd_number & 1 ) will be one always and also ( even_number & 1 ) is zero.

C program to check odd or even using bitwise operator

#include<stdio.h>
 
main()
{
   int n;
 
   printf("Enter an integer\n");
   scanf("%d",&n);
 
   if ( n & 1 == 1 )
      printf("Odd\n");
   else
      printf("Even\n");
 
   return 0;
}

Find odd or even using conditional operator

#include<stdio.h>
 
main()
{
   int n;
 
   printf("Input an integer\n");
   scanf("%d",&n);
 
   n%2 == 0 ? printf("Even\n") : printf("Odd\n");
 
   return 0;
}

C program to check odd or even without using bitwise or modulus operator

#include<stdio.h>
 
main()
{
   int n;
 
   printf("Enter an integer\n");
   scanf("%d",&n);
 
   if ( (n/2)*2 == n )
      printf("Even\n");
   else
      printf("Odd\n");
 
   return 0;
}

In c programming language when we divide two integers we get an integer result, For example the result of 7/3 will be 2.So we can take advantage of this and may use it to find whether the number is odd or even. Consider an integer n we can first divide by 2 and then multiply it by 2 if the result is the original number then the number is even otherwise the number is odd. For example 11/2 = 5, 5*2 = 10 ( which is not equal to eleven), now consider 12/2 = 6 and 6 *2 = 12 ( same as original number). These are some logic which may help you in finding if a number is odd or not.

C program to add two numbers

C program to add two numbers: This c language program perform the basic arithmetic operation of addition on two numbers and then prints the sum on the screen. For example if the user entered two numbers as 5, 6 then 11 (5 + 6) will be printed on the screen.

C programming code

#include<stdio.h>
 
int main()
{
   int a, b, c;
 
   printf("Enter two numbers to add\n");
   scanf("%d%d",&a,&b);
 
   c = a + b;
 
   printf("Sum of entered numbers = %d\n",c);
 
   return 0;
}

Download Add numbers program executable.

Output of program:

Addition without using third variable

#include<stdio.h>
 
main()
{
   int a = 1, b = 2;
 
   /* Storing result of addition in variable a */
 
   a = a + b;
 
   /* Not recommended because original value of a is lost  
    * and you may be using it somewhere in code considering it 
    * as it was entered by the user. 
    */
 
   printf("Sum of a and b = %d\n", a);
 
   return 0;
}

C program to add two numbers repeatedly

#include<stdio.h>
 
main()
{
   int a, b, c;
   char ch;
 
   while(1)
   {
      printf("Enter values of a and b\n");
      scanf("%d%d",&a,&b);
 
      c = a + b;
 
      printf("a + b = %d\n", c);
 
      printf("Do you wish to add more numbers(y/n)\n");
      scanf(" %c",&ch);
 
      if ( ch == 'y' || ch == 'Y' )
         continue;
      else
     break;
   }
 
   return 0;
}

Adding numbers in c using function

#include<stdio.h>
 
long addition(long, long);
 
main()
{
   long first, second, sum;
 
   scanf("%ld%ld", &first, &second);
 
   sum = addition(first, second);
 
   printf("%ld\n", sum);
 
   return 0;
}
 
long addition(long a, long b)
{
   long result;
 
   result = a + b;
 
   return result;
}

We have used long data type as it can handle large numbers, if you want to add still larger numbers which doesn't fit in long range then use array, string or other data structure.