In c, we can divide a large program into the basic building blocks known as function. The function contains the set of programming statements enclosed by {}. A function can be called multiple times to provide reusability and modularity to the C program. In other words, we can say that the collection of functions creates a program. The function is also known as procedureor subroutinein other programming languages
There are three aspects of a C function.
#include <stdio.h>
/* Function declaration */
double cube(double num);
int main()
{
int num;
double c;
/* Input number to find cube from user */
printf("Enter any number: ");
scanf("%d", &num);
c = cube(num);
printf("Cube of %d is %.2f", num, c);
return 0;
}
/**
* Function to find cube of any number
*/
double cube(double num)
{
return (num * num * num);
}
#include <stdio.h>
#include <math.h>
/* Function declarations */
int isPrime(int num);
int isArmstrong(int num);
int isPerfect(int num);
int main()
{
int num;
printf("Enter any number: ");
scanf("%d", &num);
// Call isPrime() functions
if(isPrime(num))
{
printf("%d is Prime number.\n", num);
}
else
{
printf("%d is not Prime number.\n", num);
}
// Call isArmstrong() function
if(isArmstrong(num))
{
printf("%d is Armstrong number.\n", num);
}
else
{
printf("%d is not Armstrong number.\n", num);
}
// Call isPerfect() function
if(isPerfect(num))
{
printf("%d is Perfect number.\n", num);
}
else
{
printf("%d is not Perfect number.\n", num);
}
return 0;
}
/**
* Check whether a number is prime or not.
* Returns 1 if the number is prime otherwise 0.
*/
int isPrime(int num)
{
int i;
for(i=2; i<=num/2; i++)
{
/*
* If the number is divisible by any number
* other than 1 and self then it is not prime
*/
if(num%i == 0)
{
return 0;
}
}
return 1;
}
/**
* Check whether a number is Armstrong number or not.
* Returns 1 if the number is Armstrong otherwise 0.
*/
int isArmstrong(int num)
{
int lastDigit, sum, originalNum, digits;
sum = 0;
originalNum = num;
/* Find total digits in num */
digits = (int) log10(num) + 1;
/*
* Calculate sum of power of digits
*/
while(num > 0)
{
// Extract the last digit
lastDigit = num % 10;
// Compute sum of power of last digit
sum = sum + round(pow(lastDigit, digits));
// Remove the last digit
num = num / 10;
}
return (originalNum == sum);
}
/**
* Check whether the number is perfect number or not.
* Returns 1 if the number is perfect otherwise 0.
*/
int isPerfect(int num)
{
int i, sum, n;
sum = 0;
n = num;
for(i=1; i<n; i++)
{
/* If i is a divisor of num */
if(n%i == 0)
{
sum += i;
}
}
return (num == sum);
}
#include <stdio.h>
/* Function declaration */
int lcm(int a, int b);
int main()
{
int num1, num2, LCM;
/* Input two numbers from user */
printf("Enter any two numbers to find lcm: ");
scanf("%d%d", &num1, &num2);
/*
* Ensures that first parameter of LCM function
* is always less than second
*/
if(num1 > num2)
LCM = lcm(num2, num1);
else
LCM = lcm(num1, num2);
printf("LCM of %d and %d = %d", num1, num2, LCM);
return 0;
}
/**
* Recursive function to find lcm of 'a' and 'b'.
* Here 'a' needs to be always less than 'b'.
*/
int lcm(int a, int b)
{
static int multiple = 0;
/* Increments multiple by adding max value to it */
multiple += b;
/*
* Base condition of recursion
* If found a common multiple then return the multiple.
*/
if((multiple % a == 0) && (multiple % b == 0))
{
return multiple;
}
else
{
return lcm(a, b);
}
}
#include <stdio.h>
/* Function declaration */
unsigned long long fibo(int num);
int main()
{
int num;
unsigned long long fibonacci;
/* Input a number from user */
printf("Enter any number to find nth fiboacci term: ");
scanf("%d", &num);
fibonacci = fibo(num);
printf("%d fibonacci term is %llu", num, fibonacci);
return 0;
}
/**
* Recursive function to find nth Fibonacci term
*/
unsigned long long fibo(int num)
{
if(num == 0) //Base condition
return 0;
else if(num == 1) //Base condition
return 1;
else
return fibo(num-1) + fibo(num-2);
}
#include<stdio.h>
int reverse_function(int num);
int main(){
int num,reverse_number;
//User would input the number
printf("\nEnter any number:");
scanf("%d",&num);
//Calling user defined function to perform reverse
reverse_number=reverse_function(num);
printf("\nAfter reverse the no is :%d",reverse_number);
return 0;
}
int sum=0,rem;
int reverse_function(int num){
if(num){
rem=num%10;
sum=sum*10+rem;
reverse_function(num/10);
}
else
return sum;
return sum;
}
#include <stdio.h>
// function declarations
int getNumber();
int square(int n);
void display(int n, int sqr);
int main()
{
int num = getNumber();
int result = square(num);
display(num, result);
return 0;
}
// function for get input from the user
int getNumber()
{
int n;
printf("Enter an Integer number: ");
scanf("%d",&n);
return n;
}
// function for finding square value
int square(int n)
{
return n*n;
}
// function for displaying result
void display(int n, int sqr)
{
printf("Square of %d = %d\n", n, sqr);
}
#include <stdio.h>
int check(int a);
int main()
{
int n, j, flag;
printf("Enter a number: ");
scanf("%d",&n);
// divide number into two parts j and (n-j)
// such as n = j + (n-j)
for(j=2;j<=n/2;j++)
{
// condition for j to be a prime number
if(check(j)==0)
{
// condition for n-j to be a prime number
if(check(n-j)==0)
{
// n= j + (n-j)
printf(" %d + %d = %d\n", j, n-j, n);
flag=0;
}
}
}
if(flag==1)
printf("Can't be sum of two prime Numbers.\n");
return 0;
}
int check(int a)
{
int i, flag=0;
for(i=2;i<=a/2;i++)
{
if(a%i==0)
flag++;
}
if(flag==0)
return 0;
else
return 1;
}
#include<stdio.h>
// function declaration
float absolute(int n);
int main()
{
int num, result;
printf("Enter a number: ");
scanf("%d", &num);
result = absolute(num); //function calling
printf("Absolute value of %d = %d\n", num, result);
return 0;
}
// function definition
float absolute(int n)
{
if(n<0) return -n;
else return n;
}
#include <stdio.h>
// function declaration
float findArea(float l, float b);
int main()
{
float length, width, result;
printf("Enter the length and width of the rectangle: ");
scanf("%f %f", &length, &width);
result = findArea(length, width); //function calling
printf("Area of rectangle = %.2f\n",result);
return 0;
}
// function to find ara of rectangle
// function definition
float findArea(float l, float b)
{
float area;
area = l * b;
return area; //return statement
}