Question

Please answer these

The following array is declared: int grades[20];

a. Write a printf() statement that can be used to display values of the first, third, and seventh elements of the array.

b. Write a scanf() statement that can be used to enter values into the first, third, and seventh elements of the array.

c. Write a for loop that can be used to enter values for the complete array. d. Write a for loop that can be used to display values for the complete array.

Write a C function reverse() that reverse the values in the input array. The array is assumed to be of integer type. The function reverse() should have two arguments. The first argument is the integer array and the second is the number of elements in the array

Write a C program that performs the following tasks: a. Stores the following numbers into a file named result.dat: 16.25, 18.96, 22.34, 18.94, 17.42, 22.63. You need to open the file for write only. Do not forget to check if the file open is successful or not. After writing is complete, close the file. b. Open the file result.dat for read only. Read, compute and display the sum and average of the data. Your program should check if the fopen() is successful as well as use a while statement that uses the EOF marker as a sentinel to read the data

Answer 1

1)ARRAY PROGRAM

CODE:

OUTPUT:

Raw_code:

//including the stdio.h for input and output function
#include<stdio.h>
//function prototypr for reverse with parameters an integer array and an integer variable
void reverse(int *,int );
int main()
{
   //integer array grades with size 20
   int grades[20];
   int i;
   //b
   //scanf statement that can be used to enter the values into the first , third and seventh
   //elements of the array
   printf("Enter the first , third and seventh values:");
   scanf("%d %d %d",&grades[0],&grades[2],&grades[6]);
   //a
   //printf statement that can be used to display the values of first, third and seventh elements of
   //the array
   printf("\nthe first element is %d\nthe second element is %d\nthe seventh element is %d\n",grades[0],grades[2],grades[6]);
   //c
   //for loop that can be used to enter the values for complete the array
   for(i=0;i<20;i++)
   {
       printf("Enter the value for grades[%d]:",i);
       scanf("%d",&grades[i]);
   }
   //d
   //for loop that displays the values for the complete the array
   for(i=0;i<20;i++)
   {
       printf("\ngrades[%d]:%d",i,grades[i]);
   }
   int size=20;
   //calling reverse function with grades array's base address and size of the grades array
   reverse(grades,size);
   //display the array elements after calling reverse function
   printf("\nThe array elements:");
   for(i=0;i<20;i++)
   {
       printf("\ngrades[%d]:%d",i,grades[i]);  
   }
   return 0;
}
//function definition to reverse the array elements
void reverse(int a[],int n)
{
   //declaring an integer array with size n
   int b[n];
   int i,j;
   //logic to store reverse the array
   for(i=n-1,j=0;i>=0;i--,j++)
   {
       b[j]=a[i];
   }
   for(i=0;i<n;i++)
   {
       a[i]=b[i];
   }
}

2)

CODE:

FILE PROGRAM

Raw_code:

//including stdio.h for input and output functions
#include<stdio.h>
//including stdlib.h for FILE manipulating functions and exit functions
#include<stdlib.h>
//starting of main function
int main()
{
   //decalring FILE pointer
   FILE *fptr;
   //store the values in an array
   double result[]={16.25,18.96,22.34,18.94,17.42,22.63};
   //opening a program.dat file in write mode
   fptr=fopen("program.dat","w");
   //if there is no file is found with that name a new file is created
   if(fptr==NULL)
   {
       printf("Error");
       exit(1);
   }
   //if the file exists
   else
   {
       //integer variable size to store the size of results array
       int size=sizeof(result)/sizeof(double);
       //integer variable i for iteration purpose
       int i;
       for(i=0;i<size;i++)
       {
           //storing the values in the result.dat
           fprintf(fptr,"%.2lf ",result[i]);
       }
   }
   //writing is complete then closing the file
   fclose(fptr);
   //open the result.dat file in read mode
   //if there is no file is found then it exit from the program with appropriate message
   if((fptr=fopen("program.dat","r"))==NULL)
   {
       printf("Error opening file");
       exit(1);
   }
   //if the file is found then else statement is executed
   //compute and display the sum and average
   else
   {
       //double varaible to store the sum
       double sum=0;
       //double variable to store the average
       double average;
       //double varaible to store the reading number from file
       double num;
       //double variable to store the number of integers in tge file
       double count;
       //while statement that uses the EOF marker as a sentinel to read the data
       while(fscanf(fptr,"%lf",&num) != EOF)
       {
           //store the sum of numbers
           sum = sum + num;
           //incrementing the count
           count = count + 1;
           //printing the each value that we read from the file
           printf("\nvalue:%lf",num);
       }
       //computing the average
           average = sum / count;
           //displaying the sum and average
           printf("\nSum = %lf Average = %lf\n",sum,average);
           //close the file
           fclose(fptr);
   }
   //return 0 to the operating system after successful compilation
       return 0;
}

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