C Prog Hub

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Reverse a given number

#include <stdio.h> #include <math.h> int main() { int n, n2 = 0 , rem; printf("Enter a number : "); scanf("%d" , &n ); while( n > 0 ) { rem = n % 10; n2 = n2 * 10 + rem; n = n / 10; } printf("\n\nThe reversed number is : %d\n\n", n2); } Link : https://repl.it/@nithin_gudla/reverseanumber

Sum of digits in a number

#include <stdio.h> #include <math.h> int main() { int n, sum = 0, rem; printf("Enter a number : "); scanf("%d" , &n ); while( n > 0 ) { rem = n % 10; sum = sum + rem; n = n / 10; } printf("\n\nThe sum is : %d\n\n", sum); } Link : https://repl.it/@nithin_gudla/sumofdigits

Prime numbers from 1 to 'n'

#include <stdio.h> #include <math.h> int main() { int n, flag, count = 0; printf("Enter a number : "); scanf("%d" , &n ); printf("\n\nThe prime numbers from 1 to %d are : \n\n", n ); for(int i = 2; i <= n ; i++ ) { flag = 0; for(int j = 2 ; j <= sqrt(i) ; j++ ) { if( i % j == 0 ) { flag = 1; break; } } if(flag == 0) { printf("%d ", i); count++; } } printf("\n\nTotal count : %d\n\n", count); } Link : https://repl.it/@nithin_gudla/prime

Given Number is Prime or Not (Efficient Algorithm)

#include <stdio.h> #include <math.h> int main() { int n, flag = 0; printf("Enter a number : "); scanf("%d" , &n ); if(n < 2) { printf("\nNumber should be greater than 2"); return 0; } for(int i = 2 ; i <= sqrt(n) ; i++ ) { if( n % i == 0 ) { flag = 1; break; } } if(flag == 0) printf("\n%d is a Prime number", n); else printf("%d is not a Prime number", n); } Link : https://repl.it/@nithin_gudla/primeefficient

Given number is Prime or Not (General Procedure)

#include <stdio.h> int main() { int n, count = 0; printf("Enter a number : "); scanf("%d" , &n ); for(int i = 2 ; i < n; i++ ) { if( n % i == 0 ) count++; // counting the number of factors. } if( count == 0 ) printf("\n%d is a Prime number", n); else printf("%d is not a Prime number", n); } Link : https://repl.it/@nithin_gudla/primegeneral

Factors of a number

#include <stdio.h> int main() { int n; printf("Enter the value of n : "); scanf("%d" , &n ); printf("\nThe factors of %d are : \n\n", n ); for(int i = 1 ; i <= n; i++ ) { if( n % i == 0 ) printf("%d ", i); } } Link : https://repl.it/@nithin_gudla/factors

Multiplication table of 'n'

#include <stdio.h> int main() { int n; printf("Enter the value of n : "); scanf("%d" , &n ); printf("\n"); for(int i = 1 ; i <= 10; i++ ) { printf("%d * %d = %d\n", n, i, n*i ); } } Link : https://repl.it/@nithin_gudla/multiplicationtable

'k' th power of 'n' - ( n ^ k )

#include <stdio.h> int main() { int n, k, result; printf("Enter the value of n : "); scanf("%d" , &n ); printf("\nEnter the value of k : "); scanf("%d" , &k ); printf("\n"); result = n; for(int i = 1 ; i < k; i++ ) { result = result * n; } printf("%d ^ %d is %d", n, k, result); } Link : https://repl.it/@nithin_gudla/power

Factorial of a number

#include <stdio.h> int main() { int n, fact = 1; printf("Enter the value of n : "); scanf("%d" , &n ); printf("\n"); for(int i = 1 ; i <= n; i++ ) { fact = fact * i; } printf("The factorial of %d is %d", n, fact); } Link : https://repl.it/@nithin_gudla/factorial

Sum of 'n' natural numbers

#include <stdio.h> int main() { int n, sum = 0; printf("Enter the value of n : "); scanf("%d" , &n ); printf("\n"); for(int i = 1 ; i <= n; i++ ) { sum = sum + i; } printf("The sum of %d natural numbers is %d", n, sum); } Link : https://repl.it/@nithin_gudla/sumnnaturalnumbers

Display even numbers from 1 to 'n'

#include <stdio.h> int main() { int n; printf("Enter the value of n : "); scanf("%d" , &n ); printf("\n"); for(int i = 1 ; i <= n; i++ ) { if(i % 2 == 0) printf("%d " , i ); } } Link : https://repl.it/@nithin_gudla/evennumbers

Display numbers from 1 to 'n'

#include <stdio.h> int main() { int n; printf("Enter the value of n : "); scanf("%d" , &n ); printf("\n"); for(int i = 1 ; i <= n; i++ ) { printf("%d " , i ); } } Link : https://repl.it/@nithin_gudla/numbers1n

Display numbers from 1 to 100

#include"stdio.h" int main() { for(int i = 1; i <= 100 ; i++ ) { printf("%d ", i); } return 0; } Link : https://repl.it/@nithin_gudla/numbers1100

Display all alphabets

#include"stdio.h" int main() { for(char ch = 'A'; ch <= 'Z' ; ch++ ) { printf("%c ", ch); } return 0; } Link : https://repl.it/@nithin_gudla/alphabets

Display "Hello World" 5 times

#include<stdio.h> int main() { for(int i = 1; i <= 5; i++) { printf("Hello World"); printf("\n"); // New Line for each iteration. } return 0; } Link : https://repl.it/@nithin_gudla/helloworld5times

Loops in C

When we want to perform a similar task multiple times, we can use the concept of loops. Basically there are three types of loops in C language. 1. For loop 2. While loop 3. Do - While loop We can also implement loops inside other loops which is known as nested loops concept. For Loop : The syntax for the "for" loop is for ( initialization ; condition ; increment / decrement / changes ) { // Statements to be executed repeatedly } The for loop is executed repeatedly until the condition becomes false. While Loop : The syntax for the "while" loop is while( condition ) { // Statements to be executed repeatedly } The while loop is executed repeatedly until the condition becomes false. Do - While Loop : The syntax for the "do - while" loop is do { // Statements to be...

Largest of three numbers

#include <stdio.h> int main() { int a, b, c, largest; printf ("Enter three numbers : "); scanf ("%d%d%d", &a, &b, &c); largest = a; // Let 'a' be the largest number if(b > largest) largest = b; if(c > largest) largest = c; printf ("\n%d is the largest number.", largest); // To find the smallest number, replace '>' with '<' return 0; } Link : https://repl.it/@nithin_gudla/largest3numbers Enter three numbers : 52 98 64 98 is the largest number.

Compare two numbers

#include <stdio.h> int main() { int a,b; printf("Enter two numbers : "); scanf("%d%d", &a, &b); if(a > b) printf("\n%d is greater than %d.", a, b); else printf("\n%d is greater than %d.", b, a); return 0; } Enter two numbers : 5 7 7 is greater than 5.

Leap year or not

#include <stdio.h> int main() { int year; printf("Enter year : "); scanf("%d", &year); if (((year % 4 == 0) && (year % 100!= 0)) || (year % 400 == 0)) printf("\n%d is a leap year", year); else printf("\n%d is not a leap year", year); return 0; } Link : https://repl.it/@nithin_gudla/leapyear Enter year : 2020 2020 is a leap year.

Whether a character is Vowel or Consonant

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

Swapping (Exchanging) of two numbers without using a third variable

#include <stdio.h> int main() { int a,b; printf("Enter two numbers "); scanf("%d%d", &a, &b ); printf("\nBefore swapping, a = %d and b = %d", a, b); a = a + b; b = a - b; a = a - b; printf("\nAfter swapping, a=%d and b=%d", a, b); return 0; } Enter two numbers 7 9 Before swapping, a = 7 and b = 9 After swapping, a=9 and b=7

Swapping (Exchanging) of two numbers using third variable

#include <stdio.h> int main() { int a,b,c; printf("Enter two numbers "); scanf("%d%d", &a, &b ); printf("\nBefore swapping, a = %d and b = %d", a, b); c = a; a = b; b = c; printf("\nAfter swapping, a=%d and b=%d", a, b); return 0; } Enter two numbers 3 4 Before swapping, a = 3 and b = 4 After swapping, a=4 and b=3

Given number is even or odd

#include <stdio.h> int main() { int n; printf("Enter a number\t:\t"); scanf("%d", &n); if(n % 2 == 0) printf("\n%d is an even number", n); else printf("\n%d is a odd number", n); return 0; } Enter a number : 5 5 is a odd number

Given number is +ve or -ve

#include <stdio.h> int main() { int n; printf("Enter a number\t:\t"); scanf("%d", &n ); if(n == 0) printf("\n%d is a neutral number", n); else if(n > 0) printf("\n%d is a positive number", n); else printf("\n%d is a negative number", n); return 0; } Enter a number : -6 -6 is a negative number

Area and Perimeter of a circle

#include <stdio.h> #define pi 3.14 // defining pi=3.14 int main() { float radius,area,perimeter; printf("Radius\t:\t"); scanf("%f", &radius); area = pi*radius*radius; perimeter = 2*pi*radius; printf("\nArea\t\t:\t%.2f", area); printf("\nPerimeter\t:\t%.2f", perimeter); return 0; } Radius : 5 Area : 78.50 Perimeter : 31.40

Area and Perimeter of a Rectangle

#include <stdio.h> int main() { float length, breadth, area, perimeter ; printf("Length\t:\t"); scanf("%f", &length ); printf("Breadth\t:\t"); scanf("%f", &breadth ); area=length*breadth; perimeter=2*( length + breadth ); printf("\nArea\t:\t%f", area); printf("\nPerimeter\t:\t%f", perimeter); return 0; } Length : 5.64 Breadth : 4.86 Area : 27.41 Perimeter : 21.00

Division of two numbers

#include <stdio.h> int main() { int a,b,rem,quo; float finalresult; printf("Enter two numbers\t:\t"); scanf("%d%d", &a , &b ); quo=a / b; rem=a % b; finalresult=(float) a / b; printf("\nQuotient\t:\t%d", quo); printf("\nRemainder\t:\t%d", rem); printf("\nFinal Result\t:\t%f", finalresult); return 0; } Enter two numbers : 24 9 Quotient : 2 Remainder : 6 Final Result : 2.666667

Absolute difference between two numbers

#include <stdio.h> #include<stdlib.h> // since we are using abs() function int main() { int a,b,c; printf("Enter two numbers\t:\t"); scanf("%d%d", &a , &b ); c= abs (a - b); printf("The absolute difference between %d and %d is %d", a, b, c); return 0; } Enter two numbers : 5 6 The average of 5 and 6 is 1

Difference between two numbers

#include <stdio.h> int main() { int a, b, c; printf("Enter two numbers\t:\t"); scanf("%d%d", &a , &b ); c = a - b; printf("The difference between %d and %d is %d", a, b, c); return 0; } Enter two numbers : 5 6 The average of 5 and 6 is -1

Average of two numbers

#include <stdio.h> int main() { int a, b; float avg; printf("Enter two numbers\t:\t"); scanf("%d%d", &a , &b ); avg = (float) (a + b) / 2; printf("The average of %d and %d is %f", a, b, avg); return 0; } Enter two numbers : 5 6 The average of 5 and 6 is 5.500000

Addition of two numbers

#include <stdio.h> int main() { int a, b, c; printf("Enter two numbers\t:\t"); scanf("%d%d", &a , &b ); c= a + b; printf("The sum of %d and %d is %d", a, b, c); return 0; } Enter two numbers : 2 3 The sum of 2 and 3 is 5

Read and display a character from the keyboard

#include<stdio.h> int main() { char ch; printf("Enter a character\t:\t"); scanf("%c", &ch ); printf("The character you have entered is %c", ch); return 0; } Enter a character : m The character you have entered is m

Read and display a number from the keyboard

#include<stdio.h> int main() { int n; printf("Enter a number\t:\t"); scanf("%d", &n ); printf("The number you have entered is %d", n); return 0; } Enter a number : 5 The number you have entered is 5

'int main()' and 'void main()'

In C programming both the 'int main()' and 'void main()' are accepted. 'void main()' means that the main function doesn't return anything. void main() { // statements } 'int main()' says that the main function will return an integer to the operating system. For that we will return an integer to the operating system. int main() { // statements return 0; // since 0 is an integer } Some compilers are designed in such a way that they can't accept main function without returning anything, for those compilers we have to use 'int main()'.

Read input from the keyboard

To read input from the keyboard, we have to use a pre-defined function "scanf()". The syntax for "scanf()" function is scanf("format string", arguments list); A format string can be : %d (integer), %s (string) , %f (floating point number), %c (character) , %lf etc. Ex : scanf("%d", &input); // for single input Here '%d' represents an integer and 'input' is the name assigned to that integer. scanf("%d%c", &input1 , &input2 ); // for multiple inputs To use 'scanf()' function also, we have to include a header file "stdio.h", i,e #include<stdio.h> or #include"stdio.h"

How to print in next line

To print text in new line, we use '\n' character which moves the cursor to the next line. #include <stdio.h> int main() { printf("Hello\nWorld!"); return 0; } OUTPUT : Hello World! Similarly '\t' generates one tab space in a line.

Let us print "Hello World!"

#include <stdio.h> int main() { printf("Hello, World!"); return 0; } Hello, World!

How to display text on monitor

We can display the text on monitor/ screen using a standard library function "printf()". The syntax for the "printf()" statement is printf(" "); printf(" Hi "); The above statement displays "Hi' on monitor. printf("format string", arguments list ); A format string can be : %d (integer), %s (string) , %f (floating point number), %c (character) , %lf etc. Ex : printf ( " %d " , output); // for single output Here '%d' represents an integer and 'output' is the name assigned to that integer. printf("%d%c", output1 , output2 ); // for multiple outputs To use printf statement in our program, we have to include a header file "stdio.h" i.e #include<stdio.h> or #include"stdio.h"

Basic Syntax for any program

#include <stdio.h> int main() { // Set of statements return 0; }