Question

Exercise #2:

1. Create a data file named water.dat with the following data: 123 134 122 128 111 110 98 99 78 98 100 120 122 110 111 123 134 122 128 111 110 98 99 78 98 100 120 122 110 111. Each number represents the number of millions of gallons of water provided to a major city over the period of one month. The data runs for quite a number of months. You will write a loop to read all the data into an array of length 50 named monthly_water_arr. Your code should count the number of data elements input, putting that value into the variable num_months and after the entire set of data has been entered, write another loop controlled by num_months to print out the values. Provide an appropriate label so you can recognize the output.

2. Extend your code by writing a loop which will go through the data in monthly_water_arr and use an if statement in the loop to print out any values between 71 and 80, inclusive.

3. Modify your code by removing the printing from this latest loop, replacing it by code to count into a variable named count_0 how many values, between 71 and 80, inclusive, would have been printed. When the loop terminates,it will print out the variable count_0. (You will shortly see why "0" is used for this name.) Try this with the data.

4. Further modify the loop by summing into another variable count_1, the number of values between 81 and 90 and after the loop terminates, print it out along with count_0. (There are none for this data so you should see 0 being printed for the second count.)

5. Next, instead of individual summing elements count_0 and count_1, create an array named count_arr which is 7 elements in length. Before summing any of the count elements in the array, use a for loop to ensure that you zero all these elements. Further modify your loop running over the array monthly_water_arr to count the elements with values between 71 and 80 into the first count_arr element (count_arr[0]), and to count the elements between 81 and 90 into the second count_arr element (count_arr[1]), and so on. Remember, a counting loop is just a sum loop which adds one (or uses ++) each time a count is to be added in. Note from inspecting the data you can see that there are 7 "bins", grouped in 10's of millions of gallons of water per bin, into which the water usage amount can fall: 71-80 , 81-90, ... , 131-140 so 7 bins will suffice for count_arr. When the loop doing the counting is finished, use a for loop to print out the 7 values in count_arr, each on a separate line. These values are the frequency in months that showed this amount of water usage per month over the observation period, in groups of 10 million gals per day. Label each number with the millions of gallons range it covers. For the given data this would look like

10 M gals water per day
71-80
81-90
91-100
101-110
111-120
121-130
131-140

6. To produce the output with the labelling column on the left is not terribly trivial, as you will have to change the label for each iteration of the printing for loop. You can do this with a series of nested if statements or you can use variables to produce the labelling numbers, changing the values in those variables with each for loop iteration.

7. As an additional challenge in the original form of this lab, see if you can produce the same result but this time only print out non-zero lines, as in

10 M gals water per day
71-80
91-100
101-110
111-120
121-130
131-140

Answer 1

#include <stdio.h>

#include <limits.h>

void tenfold(int *a1, int *a2,int size); /*HOMEWORK*/

int main(void) {

   /*Part 1*/

   double x_arr[10],xhigh = LONG_MIN, temp, xlow = LONG_MAX,x_second_arr[10],max,min,norm_x_arr[10] ; /*Smallest 32-bit number.*/

   FILE * i = fopen("TestData.txt","r");

   unsigned int count = 0;

   if (i == NULL) {

      fprintf(stderr,"Could not find file\n");

      return(1);

   }

   

   while ( !feof(i) ) { //This is another way of testing end of file.

      fscanf(i,"%lf",&x_arr[count]);

      count++;

   }

   

   puts("number | 3*number"); //Formatting columns.

   for (count = 0; count < 10; ++count) {

      temp = *(x_arr+count); //Another way to get the element from the array.

      if (xhigh < temp) {

         xhigh = temp;

      }

      if (xlow > temp) {

         xlow = temp;

      }

      x_second_arr[count] = *(x_arr + count) * 3;

      printf("%6.5lf %6.5lf\n",temp, x_second_arr[count]);

   }

   printf("The highest number in the array is %.3lf. The lowest is %.4lf\n",xhigh,xlow);

   

   puts("Now enter the new max and min you want your dataset to be normalized to: ");

   scanf("%lf %lf",&max,&min);

   

   puts("Your normal numbers are: ");

   for (count = 0; count < 10; count++) {

      *(norm_x_arr + count) = min + ((x_arr[count] - xlow) * (max-min))/(xhigh-xlow);

      printf("%.4lf\n",norm_x_arr[count]);

   }

   puts("\n");

   fclose(i);

   

   /*Part 2*/

   int monthly_water_arr[50],num_months = 0,c,temp2, small = 61;

   static int count_arr[7];

   

   FILE *j = fopen("water.dat","r");

   if (j == NULL) {

      fprintf(stderr,"Could not find file\n");

      return(1);

   }

   while (!feof(j)) {

      fscanf(j,"%d",&monthly_water_arr[num_months]);

      num_months++;

   }

   //puts("\"__\" indicates values between 71 and 80, inclusive.");

   for (c = 0; c < num_months; c++) {

      temp2 = monthly_water_arr[c];

      printf("%d\n",temp2);

      

      if (temp2 >= 71 && temp2 <= 80) {

         count_arr[0]++;

         //printf("__\n");

      }

      else if (temp2 <= 90) {

         count_arr[1]++;

      }

      else if (temp2 <= 100) {

         count_arr[2]++;

      }

      else if (temp2 <= 110) {

         count_arr[3]++;

      }

      else if (temp2 <= 120) {

         count_arr[4]++;

      }

      else if (temp2 <= 130) {

         count_arr[5]++;

      }

      else if (temp2 <= 140) {

         count_arr[6]++;

      }

      /*

      else {

      puts("");

      }*/

   }

   puts("\n10 M gals water per day: ");

   for (c = 0; c < 7; c++) {

      small += 10;

      if (count_arr[c] == 0) {

         continue;

      }

      printf("%d-%d: ",small,small+9);

      printf("%d\n", count_arr[c]);

   }

   fclose(j);

   puts("\n");

   

   /*HOMEWORK*/

   int array1[9] = {3,4,5,6,7,-8,-9,1,2}, array2[9];

   int size = 9;

   

   tenfold(array1,array2,size);

   

   return(0);

}

void tenfold(int *a1, int *a2,int size) {/*HOMEWORK*/

   int i,temp;

   for (i = 0; i < size; i++) {

      if (a1[i] > 0) {

         temp = *(a1+i) * 10;

      }

      else {

         temp = *(a1+i);

      }

      a2[i] = temp;

      printf("%d ",a2[i]);

   }

   printf("\n");

}