Question

modify the program pls so it then asks the user for another input making the program ask for a yes or no question looping it codeblocks

#include <stdio.h>

#include <ctype.h>

#define NEWLINE '\n'

int main(void)

{

   /* Declare variables and function prototypes. */

   int k=0, formula[20], n, current=0, done=0, d1, d2;

   double error=0, weight, total=0;

   double atomic_wt(int atom);

   /* Read chemical formula from keyboard. */

   printf("Enter chemical formula for amino acid: \n");

   while ((formula[k]=getchar()) != NEWLINE)

      k++;

   n = k;

   /* Identify individual elements and add weights. */

   while (current<=(n-1) && done==0)

      {

      if (isalpha(formula[current]))

      {

         formula[current] = toupper(formula[current]);

         weight = atomic_wt(formula[current]);

         if (weight == 0)

            done = 1;

         else

         {

            if (current < n-1)

               d1 = isdigit(formula[current+1]);

            else

               d1 = 0;

            if (d1 && current<(n-2))

               d2 = isdigit(formula[current+2]);

            else

               d2 = 0;

            if (d1 && d2)

            {

               weight *= ((formula[current+1]-'0')*10 +

                          (formula[current+2]-'0'));

               current += 3;

            }

          else

               if (d1)

               {

                  weight *= (formula[current+1]-'0');

                  current += 2;

               }

               else

                  current++;

         }

         total += weight;

      }

      else

         done = 1;

    }

    /* Print formula and weight. */

    printf("Formula: \n");

    for (k=0; k<=n-1; k++)

       putchar(formula[k]);

    printf("\n");

    if (done == 0)

       printf("Molecular Weight: %f \n",total);

    else

       printf("Error in formula. \n");

    /* Exit program. */

    return 0;

}

/*--------------------------------------------------------------*/

/* This function returns the molecular weight of an element    */

/* in an amino acid.                                           */

double atomic_wt(int atom)

{

   /* Declare and initialize variables. */

   int k=0, element[5]={'H','C','N','O','S'};

   char choice;

   double m_wt[5]={1.00794,12.011,14.00674,

          15.9994,32.066}, weight;

   /* Search for element. */

   while (k<=4 && element[k]!=atom)

      k++;

   /* Return corresponding atomic weight. */

   if (k <= 4)

      weight = m_wt[k];

   else

      weight = 0;

   return weight;

   }

Answer 1

The line after "printf("Error in formula.\n");" and before "return 0;", type the following lines:

printf("Enter new formula:\n");

scanf( k,n, d1, d2, weight,atom);