Learning to Program

Write a program to calculate the factorial of a number. Use the concept of recursion instead of using loops. #include <stdio.h> main ( ) { int a , fact ; printf ( " \n Enter any number: " ) ; scanf ( "%d" , & a ) ; fact = rec ( a ) ; printf ( " \n Factorial Value = %d" , fact ) ; } rec ( int x ) { int f ; if ( x = = 1 ) return ( 1 ) ; else f = x * rec ( x - 1 ) ; return ( f ) ; }

Write a recursive function to obtain the first 25 numbers of a Fibonacci sequence. In a Fibonacci sequence the sum of two successive terms gives the third term. Following are the first few terms of the Fibonacci sequence: 1 1 2 3 5 8 13 21 34 55 89 ... #include <stdio.h> main ( ) { static int prev_number = 0 , number = 1 ; // static : so value is not lost int fibonacci ( int prev_number , int number ) ; printf ( "Following are the first 25 Numbers of the Fibonacci Series: \n " ) ; printf ( "1 " ) ; // to avoid complexity fibonacci ( prev_number , number ) ; } fibonacci ( int prev_number , int number ) { static int i = 1 ; // i is not 0 , cuz 1 is already counted in main . int fibo ; if ( i = = 25 ) { printf ( " \n done" ) ; // stop after 25 numbers } else { fibo = prev_number + number ; prev_number = number ; // important steps number = fibo ; printf ( " \n %d" , fibo ) ; i + + ; // increment

Write a function that receives 5 integers and returns the sum, average and standard deviation of these numbers. Call this function from main() and print the results in main(). #include <stdio.h> #include <math.h> int calc ( float a , float b , float c , float d , float e , float * sum , float * avg , float * sd ) ; int main ( ) { float a , b , c , d , e , sum = 0.0 , avg = 0.0 ; float sd = 0.0 ; printf ( "Enter Five Numbers:" ) ; scanf ( "%f %f %f %f %f" , & a , & b , & c , & d , & e ) ; calc ( a , b , c , d , e , & sum , &amp; avg , & sd ) ; printf ( " \n Sum=%f" , sum ) ; printf ( " \n Average=%f" , avg ) ; printf ( " \n Standard Deviation=%f \n " , sd ) ; getchar ( ) ; return 0 ; } calc ( float a , float b , float c , float d , float e , float * sum , float * avg , float * sd ) { float Calc = 0.0 ; * sum = a + b + c + d + e ; * avg = * sum / 5.0 ; Calc +

This program seems to be rather simple. But there's one little thing to be noted in this particular program. The thing is that the function in this program returns a float. The function declaration is usually given outside main..but due to some other standards that I am following, I have prototyed it inside main..but that doesn't cause much of a difference in this simple program. Write a function which receives a float and an int from main(), finds the product of these two and returns the product which is printed through main(). #include <stdio.h> main ( ) { int i ; float j , prod ; float product ( int x , float y ) ; printf ( "Enter the i(int) and j(float):" ) ; scanf ( "%d %f" , & i , & j ) ; prod = product ( i , j ) ; printf ( "Product:%f" , prod ) ; } product ( int x , float y ) { float product ; product = x * y ; return ( product ) ; } The program can be found at: Download File.

The following program is one good example that illustrates how we can return more than one value in a function. The answer is certainly using Pointers. The following program demonstrates the method. Write a function that calculates both Area and Perimeter/ Circumference of the Circle, whose Radius is entered through the keyboard. #include <stdio.h> main ( ) { int radius ; float area , perimeter ; printf ( " \n Enter radius of a circle:" ) ; scanf ( "%d" , & radius ) ; areaperi ( radius , & area , & perimeter ) ; printf ( "Area=%f" , area ) ; printf ( " \n Perimeter=%f" , perimeter ) ; } areaperi ( int r , float * a , float * p ) { * a = 3.14 * r * r ; * p = 2 * 3.14 * r ; } // This Program exhibits the use of Call By Reference . The program can be found at: Download File.

A positive integer is entered through the keyboard. Write a function to obtain the prime factors of this number. For example, prime factors of 24 are 2, 2, 2 and 3, whereas prime factors of 35 are 5 and 7. #include <stdio.h> main ( ) { int number ; int prime ( int number ) ; int primefactor ( int number ) ; printf ( "Enter the number whose prime factors are to be calculated:" ) ; scanf ( "%d" , & number ) ; primefactor ( number ) ; } // The following function detects a Prime number . prime ( int num ) { int i , ifprime ; for ( i = 2 ; i < = num - 1 ; i + + ) { if ( num % i = = 0 ) { ifprime = 0 ; } else ifprime = 1 ; } return ( ifprime ) ; } // The following function prints the prime factors of a number . primefactor ( int num ) { int factor , ifprime ; for ( factor = 2 ; factor < = num ; ) { prime ( factor ) ; // so that the factors are only prime and nothing else . if ( ifprim

Write a function power(a,b), to calculate the value of a raised to b. #include <stdio.h> main ( ) { int power ( a , b ) ; int a , b , result ; printf ( "Enter the value of a and b:" ) ; scanf ( "%d %d" , & a , & b ) ; result = power ( a , b ) ; printf ( "%d raised to %d is %d" , a , b , result ) ; } power ( int a , int b ) { int calculation = 1 , calc ; for ( calc = 1 ; calc < = b ; calc + + ) { calculation = calculation * a ; continue ; } return ( calculation ) ; } The File can be found at: Download File