Tables of functions

/* Table of sines */

#include <stdio.h>
#include <math.h>
#define Pi M_PI

int main() {
   int i;
   i=1;
   do  {
   printf("%d. \t %f\n",i,sin((i/90.0)*(Pi/2)));
   i=i+1;
   } while (i <= 90);
}

Case Construction

/* A test for case */

#include <stdio.h>

int main () {
   int n;
 
   printf("Enter n (month 1--12): ");
   scanf("%d",&n);
   
   switch(n) {
      case 1 : case 2 :  case 3 : printf("Winter\n");
                   break;
      case 4 : case 5 : case 6 : printf("Spring\n");
                   break;
      case 7 : case 8 : case 9 : printf("Summer\n");
                   break;
      case 10 : case 11: case 12 : printf("Fall\n");
                   break;
      }
    }

#include <stdio.h>

int main () {

 int i, n;
 float sum;

 n = 10000;
 i = 1;
 sum = 0.0;

while (i <= n) {

    switch( i%4 ) {
       case 0: case 2:
           break ;
       case 1:
           sum = sum + 1.0/i;
           break;
       case 3:
           sum = sum - 1.0/i;
           break;
    }
    i = i+1;
}
 printf("The sum of the series is %f.\n", sum);
}