C Programs

Determine alphabet or number Program # 1

To determine whether an input value is an alphabet or number

              
  // Check if Character is an Alphabet or not

  #include <stdio.h>
  int main() {
    // 65 - 90 A - Z ----- ASCII CODES 
    // 97 - 122 a - z
    // 48 - 57 0 - 9 
    char a;
    printf("Please Enter a character : \n");
    scanf("%c",&a);
    
    if((a >= 65 && a <= 90) || (a >= 97 && a<= 122))   
    {
      printf("It's an alphabet! \n");
    }
    else if(a >= 48 && a <= 57){
      printf("It's a number! \n");
    }
    else{
      printf("Error! \n");
    }
    
    return 0;
  }

Calculate the area of triangle and square Program # 2

Calculating the area of triangle and square by taking input value based on the user choice.

              
  // Find Area of Triangle & Square

  #include <stdio.h>
  #include <math.h>
  int main(){
    // S, s OR T, t
    char input;
    float areaOfSquare, areaOfTriangle, s, b, h;
    printf("Choose to Calculate the Area of : \n");
    printf("(S) for Square : ");
    printf("(T) for Triangle : ");
    scanf("%c",&input);
    
    if(input == 83 || input == 115){
      printf("Enter value of s : ");
      scanf("%f",&s); 
      areaOfSquare = pow(s,2);
      printf("Area of Square is %.2f : ",areaOfSquare);
    }
    else if(input == 84 || input == 116){
      printf("Enter value of height : ");
      scanf("%f",&h); 
      printf("Enter value of base : ");
      scanf("%f",&b); 
      areaOfTriangle = 0.5 * b * h;
      printf("Area of Triangle is %.2f : ",areaOfTriangle);   
    }
    else{
      printf("Error");
    }
    return 0;
  }

Printing A - Z alphabets Program # 3

Simply printing A - Z alphabets

              
  //Display Characters from A to Z Using Loop   

  #include <stdio.h>
  int main() {
    
    // ASCII will be helpful here
    char a = 65;
    for(; a <= 90; a++){
      printf("%c \t",a);
    }
    
    return 0;	
  }

Generate multiplication table Program # 4

The aim is to print a multiplication table based on the integer value given by the user

              
  //Displaying multiplication table  

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

    return 0;	
}

Check Even / Odd number Program # 5

Check if the given value is Even or Odd

              
  // Determining Even / Odd Numbers

  #include 
  int main(){
    
    int num;
    
    printf("Enter any Number : \n");
    scanf("%d",&num);
    
    if(num % 2 == 0 && num != 0){
      printf("It's an Even Number! \n");
    }
    else if(num % 2 == 1){
      printf("It's an Odd Number! \n");
    }
    else{
      printf("I think you entered Zero! \n");  
    }
    
    return 0;
  }

Find factorial of a number Program # 6

Finding the factorial of a number entered by the user

              
 // Find the Factorial of a number 

  #include 
  int main() {
      int n, i;
      unsigned long long fact = 1;
      printf("Enter an integer: ");
      scanf("%d", &n);

      if (n < 0)
          printf("Error! Factorial of a negative number doesn't exist.");  
      else {
          for (i = 1; i <= n; i++) {
              fact *= i;
          }
          printf("Factorial of %d = %llu", n, fact);
      }

      return 0;
  }

Find factors of a number Program # 7

Finding the factors of a number given by the user

              
  // Factors of a Number
  #include 
  int main() {
    
    int n;
    
    printf("Enter a number to find factors of : ");  
    scanf("%d",&n);
    
    for(int i = 1; i <= n; i++){
      if(n % i == 0){
        printf(" %d \t",i);
      }
    }

    getch();
    return 0;
}

Finding remainder Program # 8

Finding remainder and qoutient by taking values from the user

              
 // Finding Remainder & Quotient

  #include 
  int main(){
    int divisor, dividend, remainder, quotient;
    
    printf("Enter a dividend: \n");
    scanf("%d", ÷nd);
    
    printf("\n");

    printf("Enter a divisor: \n");
    scanf("%d", &divisor);
    
    remainder = dividend % divisor;
    quotient = dividend / divisor;
    
    printf("Remainder is : %d \n Quotient is : %d",remainder, quotient);   
    
    return 0;
  }

Finding size of datatypes Program # 9

Finding sizes of different data types at once.

              
  // Find the Size of int, float, double and char

  #include 
  #include 
  int main() {
    
    printf("Size of int is : %zu bytes \n",sizeof(int));
    printf("Size of float is : %zu bytes \n",sizeof(float));
    printf("Size of double is : %zu bytes \n",sizeof(double));
    printf("Size of char is : %zu bytes \n",sizeof(char));
    
    return 0;
  }

Finding the largest number Program # 10

Finding the largest number among three entered number

              
 // Finding the largest number among 3 numbers

  #include 
  int main() {
    
    int a, b, c;
    
    printf("Enter First Number : \n");
    scanf("%d",&a);
    
    printf("Enter Second Number : \n");
    scanf("%d",&b);
    
    printf("Enter Third Number : \n");
    scanf("%d",&c);
    
    if(a > b && a > c){
      printf("%d is the largest Number! \n",a);  
    }
    else if(b > a && b > c){
      printf("%d is the largest Number! \n",b);
    }
    else if(c > a && c > b){
      printf("%d is the largest Number! \n",c);
    }
    else {
      printf("Error \n");
    }
    
    return 0;
  }

Finding leap year Program # 11

Finding the leap year which comes every 4th year . Let's found out how ?

              
  // Leap Year Program

   #include 
   int main(){
	int year;
	
	printf("Enter a year: ");
	scanf("%d",&year);
	
	// YEAR SHOULD BE DIVIDED BY 4 AND 400 , NOT BY 100
	
	if((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)){
		printf("Leap Year \n");
	} 
	else {
		printf("Not Leap Year \n");
	}
	
	return 0;
}

Display series of odd numbers Program # 12

The aim is to display a series of odd number to a given number

              
  // Printing odd numbers using loop

  #include 
  int main(){
	
	int odd_numbers = 17;
	
	for(int i = 1; i <= odd_numbers; i+=2){
		printf("%d \t",i);
	}
	
	return 0;
}

Positive, negative or zero Program # 13

Determining whether a number is positive , negative or zero

              
 	// Positive , Negative OR Zero Number

  #include 
  int main() 
{
	int n;
	
	printf("Please enter a number : \n");
	scanf("%d",&n);
	
	if(n < 0){
		printf("Negative");
	}
	else if(n > 0){
		printf("Positive");
	}
	else{
		printf("Zero");
	}
	
	
}

Prime numbers between two integers Program # 14

By using a loop we will print a series of prime numbers, the initial value and ending value is determined (or entered) by the user

              
	// Prime Numbers Between two intervals
  #include 
  #include 

  int main() {
    int n1, n2, i, j, isPrime;

    printf("Enter starting number: ");
    scanf("%d", &n1);

    printf("Enter ending number: ");
    scanf("%d", &n2);

    if (n1 < 2) // To Check if n1(initial number) is less than 2. (We do not count 1 OK)
    
    n1 = 2;  // If YES start taking Prime numbers from 2
    printf("Prime numbers between %d and %d are:\n", n1, n2);
    
    for (i = n1; i <= n2; i++) {
        isPrime = 1;  // Assume i is prime. If i isPrime then apply condition below

        for (j = 2; j <= sqrt(i); j++) {		// <= Here i is all Prime numbers OK.
            if (i % j == 0) {
                isPrime = 0;  // If i is not prime then break the loop 
                break;
            }
        }

        if (isPrime) {  // If isPrime is true print all Prime numbers
            printf("%d ", i);
        }
    }

    printf("\n");
    
    getch();
    return 0;
}

Prime number or not Program # 15

Finding out that an entered value is a prime number or not , the logic is tricky but once figured out, it will be a piece of cake

              
// Prime or Not

 #include 
 #include 
 int main() {
    int n, i, isPrime = 1;

    printf("Enter a number: ");
    scanf("%d", &n);

    if (n <= 1) {
        isPrime = 0;  // 0 and 1 are not prime
    } else {
        for (i = 2; i <= sqrt(n); i++) {
            if (n % i == 0) {
                isPrime = 0;
                break;
            }
        }
    }

    if (isPrime)
        printf("%d is a prime number.", n);
    else
        printf("%d is not a prime number.", n);

    return 0;
}

Reverse a given number Program # 16

Reversing a given number, you can use a calculator to figure out each computation

              
// Reverse a Number

 #include 
 int main(){
	
	int rev = 0, num = 123;
	
	while (num != 0) {
    int digit = num % 10;        
    rev = rev * 10 + digit;       
    num = num / 10;               
	}
	
	printf("%d",rev);
	
	return 0;
}

Building a calculator using switch Program # 17

A calculator can be built in many ways, a simple calculator is built using switch conditional statements

              
// Simple Calculator Using switch...case

 #include 
 int main() {
	
	int n1, n2, op;
	
	printf("Enter first number : ");
	scanf("%d",&n1);
	
	printf("Enter second number : ");
	scanf("%d",&n2);
	
	printf("Choose Operation is be performed : \n");   
	printf("1) Division ( / ) \n");
	printf("2) Multiply ( x ) \n");
	printf("3) Addition ( + ) \n");
	printf("4) Subtraction ( - ) \n");
	
	scanf("%d",&op);
	
	switch (op){
		case 1 :
			printf("%d / %d = %d",n1,n2,n1/n2);
		break;
	
		case 2 :
			printf("%d x %d = %d",n1,n2,n1*n2);
		break;	
	
		case 3 :
			printf("%d + %d = %d",n1,n2,n1+n2);
		break;
	
		case 4 :
			printf("%d - %d = %d",n1,n2,n1-n2);
		break;
		
		default :
			printf("Error ");
	
	}
	getch();
	return 0;
}

Sum & Product of series of even numbers Program # 18

Displaying sum and product of even number series using loop, the logic is almost same for both.

              
// Sum & Product of first ten Even Numbers

 #include 

 int main(){
	int even_num = 10, sum = 0, pro = 1;
	
	// SUM Logic
	for(int i = 2; i <= even_num; i = i+2){
		printf("%d \t",i);
		sum = i + sum;
	}
	
	printf("\n Sum of even numbers : %d \n",sum);
	
	// PRODUCT Logic
		for(int j = 2; j <= even_num; j = j+2){
		printf("%d \t",j);
		pro = j * pro;
	}
	
	printf("\n Product of even numbers : %d",pro);
	
	return 0;
}

Finding sum of natural numbers Program # 19

Displaying sum of natural numbers using loop, copy the code and modify it according to you needs

              
 // Calculate the sum of natural numbers

 #include 
 int main() {
	
	int sum;
	for(int i=1; i <= 10; i++){\
		sum = i + sum;
	}
	printf("The SUM of Natural Numbers from 1 - 10 is : %d \n",sum);
	
	return 0;
}

Swaping two integers Program # 20

Interchanging the values of two variables using simple logic

              
  // Swaping Two Numbers

 #include 
 int main(){
	
	int n1, n2, n3;
	n1 = 123;
	n2 = 456;
	printf("n1 is %d and n2 is %d \n",n1,n2);
	
	// Swaping
	n3 = n1;
	n1 = n2;
	n2 = n3;
	printf("Now n1 is %d and n2 is %d \n",n1,n2);
	
	return 0;
}

Temperature conversion Program # 21

Temperature converter fehrenheit to celcius and vice versa , you only need is a formula

              
  // Fahrenheit to Celsius vice versa

 #include 
 int main(){
	
	float temperature, F, C;
	int opt;
	printf("Choose Conversion : \n");
	printf("(1) Fahrenheit to Celsius \n");
	printf("(2) Celsius to Fahrenheit \n");
	scanf("%d",&opt);
	
	if(opt == 1){
		printf("Enter Fahrenheit Temperature : ");
		scanf("%f",&F);
		temperature = 0.556 * (F - 32);
		printf(" %.2f Fahrenheit into Celsius is %.2f C",F,temperature);
	}
	else if(opt == 2){
		printf("Enter Celsius Temperature : ");
		scanf("%f",&C);
		temperature = ((1.8 * C) + 32);
		printf(" %.2f Celsius into Fahrenheit is %.2f F",C,temperature);
	}
	else {
		printf("Error");
	}
	return 0;
}

Finding out vowel or consonant Program # 22

Displaying that the entered value (character) is a vowel or a consonant, use ascii codes if you have to its a fun challenge

              
 // Determine Vowel or not

 #include 
 int main() {
	/*
	A E I O U - 65, 69, 73, 79, 85
	a e i o u - 97, 101, 105, 111, 117
	*/
	
	char vowel;
	printf("Enter any character : ");
	scanf("%c",&vowel);
	if(vowel == 65 || vowel == 97 || vowel == 69 || vowel == 101 || vowel == 73 || vowel == 105 || vowel == 79 || vowel == 111 || vowel == 85 || vowel == 117){
			printf("Vowel");
	}
	else {
		printf("Consonant");
	}
	
}

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