C/Function/Function Recursive

A recursive power function

<source lang="cpp">

1. include <stdio.h>

double power(double x, int n); int main() {

 double x = 0.0;
 int n = 0;
 for(x = 2.0 ; x<= 5.0; x += 0.5)
   for(n = 0 ; n<5 ; n++)
     printf("%.2lf raised to the power %d = %.2lf\n", x, n, power(x,n));

} /* Function to raise x to the power n.*/ double power(double x, int n) {

 if(n == 0)
   return 1.0;
 else
   return x * power( x , n - 1 );

}

      </source>

Calculating factorials using recursion

<source lang="cpp">

1. include <stdio.h>

long factorial(long); void main() {

 long number = 0;
 printf("\nEnter an integer value: ");
 scanf(" %ld", &number);
 printf("\nThe factorial of %ld is %ld\n", number, factorial(number));

} /* recursive factorial function */ long factorial(long N) {

 if( N < 2 )
   return N;
 else 
   return N*factorial(N - 1);

}

      </source>

Copy string using recursion

<source lang="cpp">

1. include <stdio.h>

void strcopy(char *s1, char *s2); int main(void) {

 char str[80];
 strcopy(str, "this is a test");
 printf(str);
 return 0;

}

void strcopy(char *s1, char *s2) {

 if(*s2) { /* if not at end of s2 */
   *s1++ = *s2++;
   strcopy(s1, s2);
 }
 else *s1 = "\0"; /* null terminate the string */

}

      </source>

Function: Recursive call

<source lang="cpp">

1. include <stdio.h>

void f(int i); int main(void) {

 f( 0 );
 return 0;

} void f(int i) {

 if( i < 10) {
   f( i + 1 ); /* recursive call */
   printf("%d ", i);
 }

}

      </source>

Prints out Fibonacci numbers

<source lang="cpp">

1. include <stdio.h>

int main() {

   int   old_number= 1;
   int   current_number = 1;
   int   next_number;
   while (current_number < 100) {
       printf("%d\n", current_number);
       next_number = current_number + old_number;
       old_number = current_number;
       current_number = next_number;
   }
   return (0);

}

      </source>

Recursive function call

<source lang="cpp">

1. include <stdio.h>

int add(int pk,int pm); main() {

  int k = 2;
  int i;
  int m = 3;
  i = add(k,m);
  printf("i =  %d\n",i);

} int add(int addk,int addm) {

   if(addm==0) 
       return(addk); 
   else 
       return(1+add(addk,addm-1));

}

      </source>

Recursive function with static variable

<source lang="cpp">

1. include <stdio.h>

void f(void); int main(void) {

 f();
 return 0;

} void f(void) {

 static int s = 0;
 s++;
 if(s == 10) 
     return;
 printf("%d ", s);
 f(); /* recursive call */

}

      </source>