Third Week Examples: More Loops, Console Input, Case Construction

While Loop

/************************************************
Treibergs                            Jan 24, 2006 
Third Week Example 1: While Loop
hello3.c 
************************************************/

# include <stdio.h>
# include <stdlib.h>

int 
main(void) 
{
   int i = 1;
   
   while (i <= 10) 
   {
       printf("%d. Hello!\n",i);
       i=i+1;
   }
   
   return EXIT_SUCCESS;
}

Do - While Loops

/************************************************
Treibergs                            Jan 24, 2006 
Third Week Example 2: Do - While Loop
hello4.c 
************************************************/

# include <stdio.h>
# include <stdlib.h>

int 
main(void) 
{
   int i = 1;
   
   do 
   {
       printf ("%d. Hello!\n",i);
       i=i+1;
   } 
   while (i <= 10);

   return EXIT_SUCCESS;
}

Console Input

/************************************************
Treibergs                            Jan 24, 2006 
Third Week Example 3: Console Input Example
evenodd.c 
************************************************/

# include <stdio.h>
# include <stdlib.h>

int 
main(void) 
{

    int n;

    printf ("Input an integer> ");
    scanf ("%d", &n);

    if (n % 2 != 1)
         printf("%d is even.\n",n);

    else
         printf("%d is odd.\n",n);

    return EXIT_SUCCESS;
}

/************************************************
Treibergs                            Jan 24, 2006 
Third Week Example 4: Interavtive Summation of 
the Alternating Harmonic Series
sum7.c 
************************************************/

# include <stdio.h>
# include <stdlib.h>

int 
main(void) 
{

    int i,n;
    float sum;
    
    sum = 0.0;

    printf ("How many terms to sum> ");
    scanf ("%d", &n);

    for (i = 1; i <= n ; i=i+1) 
    {
        if (i % 2 == 0)
           sum = sum - 1.0/i ;

        else
           sum = sum + 1.0/i;
    }

    printf("The sum of %d terms is equal to %f\n", n, sum);

    return EXIT_SUCCESS;
}

Case Construction

/************************************************
Treibergs                            Jan 24, 2006 
Third Week Example 5: Case Construction
season.c 
************************************************/

# include <stdio.h>
# include <stdlib.h>

int 
main(void) 
{
    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;
     }

     return EXIT_SUCCESS;
}

/************************************************
Treibergs                            Jan 24, 2006 
Third Week Example 6: Case Construction to Sum
1/1 - 1/3 + 1/5 - 1/7 + 1/9 - 1/11 + ...
sum8.c 
************************************************/

# include <stdio.h>
# include <stdlib.h>

int 
main(void) 
{

    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);

    return EXIT_SUCCESS;
}

/*  Treibergs      1-25-06

Program to evaluate the Taylor polynomials of
exp(x)  centered at  a

today.c   */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int 
main(void)
{
     int  i, n;
     double  x,  a,  u,  term,   sum;

     printf( " Taylors polynomials for exp(x)\n\n");
     printf(" Enter the center  a  :");
     scanf("%lf", &a);
     printf(" Enter x :");
     scanf("%lf",&x);

     n = 20;
     sum = 0.0;
     term = exp(a);
     u = x - a;

     i = 0;

     printf(" n\t\t term \t\t n th Taylor polynomial evaluated at  x\n");

     while( i <=  n)
     {
          sum = sum + term;
          printf(" %4d %21.15f  %21.15f \n", i, term, sum);
          i = i + 1;
          term = term*u/i;
     }

     printf(" \t Theoretical sum  =  %21.15f \n", exp(x));

     return EXIT_SUCCESS;
}