## C Program to Check Whether a Character is a Vowel or Consonant

Code:

```#include <stdio.h>
int main()
{
char c;
int low, upp;
printf("Enter any alphabet: ");
scanf("%c", &c);
low = (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u');
upp = (c == 'A' || c == 'E' || c == 'I' || c == 'O' || c == 'U');
if (low || upp)
{
printf("Vowel\n");
}
else
{
printf("Consonant\n");
}
return 0;
}```

Output:

```Enter any alphabet: A
Vowel```

## C Program to Find the Largest Number Among Three Numbers

Code:

```#include <stdio.h>
int main()
{
int a, b, c;
printf("Enter first no: ");
scanf("%d", &a);
printf("Enter second no: ");
scanf("%d", &b);
printf("Enter third no: ");
scanf("%d", &c);
if (a >= b && a >= c)
printf("Largest number: %d\n", a);
if (b >= a && b >= c)
printf("Largest number: %d\n", b);
if (c >= a && c >= b)
printf("Largest number is %d\n", c);
return 0;
}```

Output:

```Enter first no: 1
Enter second no: 6
Enter third no: 4
Largest number: 6```

## C Program to Find the Roots of a Quadratic Equation

Code:

```#include <math.h>
#include <stdio.h>
int main()
{
double a, b, c, disc, rt1, rt2, real, imaginary;
printf("Enter coefficients a: ");
scanf("%lf", &a);
printf("Enter coefficients b: ");
scanf("%lf", &b);
printf("Enter coefficients c: ");
scanf("%lf", &c);

disc = (b * b) - (4 * a * c);
if (disc > 0)
{
rt1 = (-b + sqrt(disc)) / (2 * a);
rt2 = (-b - sqrt(disc)) / (2 * a);
printf("rt1 = %.2lf and rt2 = %.2lf", rt1, rt2);
}
else if (disc == 0)
{
rt1 = rt2 = -b / (2 * a);
printf("First root = Second root = %.2lf;", rt1);
}
else
{
real = -b / (2 * a);
imaginary = sqrt(-disc) / (2 * a);
printf("First root = %.2lf+%.2lfi and Second root = %.2f-%.2fi", real, imaginary, real, imaginary);
}
return 0;
}```

Output:

```Enter coefficients a: 4
Enter coefficients b: 5
Enter coefficients c: 2
First root = -0.62+0.33i and Second root = -0.62-0.33i```

## C Program to Check Leap Year

Code:

```#include <stdio.h>
int main()
{
int n;
printf("Year: ");
scanf("%d", &n);
if (n % 400 == 0)
{
printf("Leap Year", n);
}
else if (n % 100 == 0)
{
printf("Not a Leap Year", n);
}
else if (n % 4 == 0)
{
printf("Leap Year", n);
}
else
{
printf("Not a Leap Year", n);
}
return 0;
}```

Output:

```Year: 2020
Leap Year```

## C Program to Check Whether a Number is Positive or Negative

Code:

```#include <stdio.h>
int main()
{
int n;
printf("Input a number: ");
scanf("%d", &n);
if (n <= 0.0)
{
if (n == 0.0)
printf("Entered number is 0\n");
else
printf("Negative number\n");
}
else
printf("Positive number\n");
return 0;
}
```

Output:

```Input a number: 5
Positive number```

## C Program to Check Whether a Character is an Alphabet or not

Code:

```#include <stdio.h>
int main()
{
char val;
printf("Enter a character value: ");
scanf("%c", &val);

if ((val >= 'a' && val <= 'z') || (val >= 'A' && val <= 'Z'))
printf("Alphabet\n", val);
else
printf("Not an alphabet\n", val);

return 0;
}
```

Output:

```Enter a character value: b
Alphabet```

## C Program to Calculate the Sum of Natural Numbers

Code:

```#include <stdio.h>
int main()
{
int n, i, add = 0;
printf("Enter a number: ");
scanf("%d", &n);
for (i = 1; i <= n; ++i)
{
add = add+i;
}
printf("Sum of natural numbers from 1 to %d is %d\n", n, add);
return 0;
}```

Output:

```Enter a number: 8
Sum of natural numbers from 1 to 8 is 36```

## C Program to Find Factorial of a Number

Code:

```#include <stdio.h>
int main()
{
int num, i;
long long unsigned int fact = 1;
printf("Enter a number: ");
scanf("%d", &num);
if (num < 0)
printf("Write a positive number.");
else
{
for (i = 1; i <= num; ++i)
{
fact *= i;
}
printf("Factorial is %llu\n", fact);
}

return 0;
}```

Output:

```Enter a number: 5
Factorial is 120```

## C Program to Generate Multiplication Table

Code:

```#include <stdio.h>
int main()
{
int a, i;
printf("Enter an integer value: ");
scanf("%d", &a);
for (i = 1; i <= 10; ++i)
{
printf("%d * %d = %d \n", a, i, a * i);
}
return 0;
}```

Output:

```Enter an integer value: 9
9 * 1 = 9
9 * 2 = 18
9 * 3 = 27
9 * 4 = 36
9 * 5 = 45
9 * 6 = 54
9 * 7 = 63
9 * 8 = 72
9 * 9 = 81
9 * 10 = 90```

## C Program to Display Fibonacci Sequence

Code:

```#include <stdio.h>
int main()
{
int i, n, term1 = 0, term2 = 1, next;
printf("Number of terms to be calculated: ");
scanf("%d", &n);
printf("This is the Fibonacci Series: ");

for (i = 1; i <= n; ++i)
{
printf("%d, ", term1);
next = term1 + term2;
term1 = term2;
term2 = next;
}
printf("\n");
return 0;
}```

Output:

```Number of terms to be calculated: 8
This is the Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13,```

## C Program to Find GCD of two Numbers

Code:

```#include <stdio.h>
int main()
{
int number1, number2, i, GCD;
printf("Enter first integer: ");
scanf("%d", &number1);
printf("Enter two integer: ");
scanf("%d", &number2);
for (i = 1; i <= number1 && i <= number2; ++i)
{
if (number1 % i == 0 && number2 % i == 0)
GCD = i;
}
printf("G.C.D: %d\n", GCD);
return 0;
}```

Output:

```Enter first integer: 5
Enter two integer: 9
G.C.D: 1```

## C Program to Find LCM of two Numbers

Code:

```#include <stdio.h>
int main()
{
int number1, number2, maximum;
printf("Enter first integer: ");
scanf("%d", &number1);
printf("Enter second integer: ");
scanf("%d", &number2);
maximum = (number1 > number2) ? number1 : number2;
while (1)
{
if (maximum % number1 == 0 && maximum % number2 == 0)
{
printf("LCM: %d\n", maximum);
break;
}
++maximum;
}
return 0;
}```

Output:

```Enter first integer: 10
Enter second integer: 20
LCM: 20```

## C Program to Display Characters from A to Z Using Loop

Code:

```#include <stdio.h>
int main()
{
char ch;
for (ch = 'A'; ch <= 'Z'; ++ch)
{
printf("%c ", ch);
}
printf("\n");
return 0;
}```

Output:

`A B C D E F G H I J K L M N O P Q R S T U V W X Y Z`

## C Program to Count Number of Digits in an Integer

Code:

```#include <stdio.h>
int main()
{
long long a;
int count = 0;
printf("Enter an integer value: ");
scanf("%lld", &a);
while (a != 0)
{
a /= 10;
++count;
}
printf("%d digits in integer\n", count);
}```

Output:

```Enter an integer value: 145
3 digits in integer```

## C Program to Reverse a Number

Code:

```#include <stdio.h>
int main()
{
int n, reverse = 0, rem;
printf("Enter an integer value: ");
scanf("%d", &n);
while (n != 0)
{
rem = n % 10;
reverse = reverse * 10 + rem;
n /= 10;
}
printf("Reverse of the number is %d\n", reverse);
return 0;
}
```

Output:

```Enter an integer value: 1984
Reverse of the number is 4891```

## C Program to Calculate the Power of a Number

Code:

```#include <stdio.h>
int main()
{
int a, n;
long long sum = 1;
printf("Base number: ");
scanf("%d", &a);
printf("Exponent: ");
scanf("%d", &n);
while (n != 0)
{
sum *= a;
--n;
}
printf("Value evaluated is %lld\n", sum);
return 0;
}```

Output:

```Base number: 8
Exponent: 3
Value evaluated is 512```

## C Program to Check Whether a Number is Palindrome or Not

Code:

```#include <stdio.h>
int main()
{
int n, reverse = 0, rem, origin;
printf("Enter an integer value : ");
scanf("%d", &n);
origin = n;
while (n != 0)
{
rem = n % 10;
reverse = reverse * 10 + rem;
n /= 10;
}
if (origin == reverse)
printf("Palindrome\n", origin);
else
printf("Not a Palindrome\n", origin);

return 0;
}```

Output:

```Enter an integer value : 5
Palindrome```

## C Program to Check Whether a Number is Prime or Not

Code:

```#include <stdio.h>
int main()
{
int num, i, k = 0;
printf("Enter a number: ");
scanf("%d", &num);
for (i = 2; i <= num / 2; ++i)
{
if (num % i == 0)
{
k = 1;
break;
}
}
if (k == 0)
printf("Prime number\n", num);
else
printf("Not a Prime number\n", num);
return 0;
}```

Output:

```Enter a number: 49
Not a Prime number```

## C Program to Display Prime Numbers Between Two Intervals

Code:

```#include <stdio.h>
int main()
{
int open, close, i, k;
printf("Enter opening intervals: ");
scanf("%d", &open);
printf("Enter closing intervals: ");
scanf("%d",&close);
printf("Prime number are ", open, close);
while (open < close)
{
k = 0;
if (open <= 1)
{
++open;
continue;
}
for (i = 2; i <= open / 2; ++i)
{

if (open % i == 0)
{
k = 1;
break;
}
}
if (k == 0)
printf("%d ", open);
++open;
}
printf("\n");
return 0;
}```

Output:

```Enter opening intervals: 1
Enter closing intervals: 20
Prime number are 2 3 5 7 11 13 17 19```

## C Program to Check Armstrong Number

Code:

```#include <math.h>
#include <stdio.h>

int main()
{
int number, original, rem, n = 0;
float result = 0.0;
printf("Enter an number: ");
scanf("%d", &number);
original = number;
for (original = number; original != 0; ++n)
{
original /= 10;
}
for (original = number; original != 0; original /= 10)
{
rem = original % 10;
result += pow(rem, n);
}
if ((int)result == number)
printf("Armstrong number\n", number);
else
printf("Armstrong number\n", number);
return 0;
}```

Output:

```Enter an number: 9
Armstrong number```

## C Program to Display Armstrong Number Between Two Intervals

Code:

```#include <math.h>
#include <stdio.h>
int main()
{
int lowest, highest, number, original, remainder, reps = 0;
double result = 0.0;
printf("Enter opening interval: ");
scanf("%d", &lowest);
printf("Enter closing interval: ");
scanf("%d", &highest);
printf("Armstrong numbers are: ", lowest, highest);
for (number = lowest + 1; number < highest; ++number)
{
original = number;
while (original != 0)
{
original /= 10;
++reps;
}
original = number;
while (original != 0)
{
remainder = original % 10;
result += pow(remainder, reps);
original /= 10;
}
if ((int)result == number)
{
printf("%d ", number);
}
reps = 0;
result = 0;
}
printf("\n");
return 0;
}```

Output:

```Enter opening interval: 5
Enter closing interval: 20
Armstrong numbers are: 6 7 8 9```

## C Program to Display Factors of a Number

Code:

```#include <stdio.h>
int main()
{
int number, i;
printf("Enter an integer: ");
scanf("%d", &number);
printf("Factors: ", number);
for (i = 1; i <= number; ++i)
{
if (number % i == 0)
{
printf("%d ", i);
}
}
printf("\n");
return 0;
}
```

Output:

```Enter an integer: 5
Factors: 1 5```

## C Program to Make a Simple Calculator Using switch…case

Code:

```#include <stdio.h>
int main()
{
char oprtr;
double n1, n2;
printf("Enter an operation to be done (+, -, *,): ");
scanf("%c", &oprtr);
printf("Enter first number: ");
scanf("%lf", &n1);
printf("Enter second number: ");
scanf("%lf", &n2);
switch (oprtr)
{
case '+':
printf("%.1lf + %.1lf = %.1lf", n1, n2, n1 + n2);
break;
case '-':
printf("%.1lf - %.1lf = %.1lf", n1, n2, n1 - n2);
break;
case '*':
printf("%.1lf * %.1lf = %.1lf", n1, n2, n1 * n2);
break;
case '/':
printf("%.1lf / %.1lf = %.1lf", n1, n2, n1 / n2);
break;
default:
printf(" oprtr is not correct");
}
printf("\n");
return 0;
}```

Output:

```Enter an operation to be done (+, -, *,): +
Enter first number: 4
Enter second number: 6
4.0 + 6.0 = 10.0```