Question

1) (10 pts) A class has n students, and the ith student has taken si tests. This information is stored in a file where the first line has the value of n and the following n lines have information about each student. On the ith of these lines, the first value is si. This is followed by si integers, all in between 0 and 100, inclusive, representing the test scores. Here is a sample file: 4 10 100 80 90 100 90 90 95 80 100 95 3 87 93 90 5 100 90 90 100 90 8 90 90 90 90 80 80 85 85 Write a segment of code that reads in this information from standard input (assuming file redirection on the command prompt as shown in class) into an array of arrays that is dynamically allocated to have precisely the correct number of slots to store the data. Name your array studentscores. All necessary variables have been declared for you below. Please use only these in your solution. Note: you are ONLY allocating the memory and reading in the information. No need to do anything else. Also, the way this is written, you wouldn't have stored the length of each separate array, but don't worry about that for the purposes of this question. int** studentscores; int i, j, numStudents, numScores;

Answer 1

I have also implemened storing lengths of each student's scores array, this is useful in printing the input data and verify whether data has been properly read and stored. The code highlighted in YELLOW is not required for this question. Since, it has been mentioned only input reading and storing is required and storing lengths is not required.

I have used malloc for dynamically allocating memory.

I have included my code and screenshots in this answer. In case, there is any indentation issue due to editor, then please refer to code screenshots to avoid confusion.

------------------main.c-----------

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

int main()
{
   int **studentscores; //similar to two dimensional array for storing scores of all studemts
   int i, j, numStudents, numScores;
   scanf("%d", &numStudents); //read numnber of students

   int *lengths; /* to store lengths of students marks araray (This is not required for this question)
   but i did it to print the entered data and verify if data is insert properly) */

   studentscores = (int **)malloc(numStudents * sizeof(int *)); //allocate space for numStudents
   lengths = (int *)malloc(numStudents * sizeof(int)); //allocate space for numStudents sized array

   for(i = 0; i < numStudents; i++) //for each student
   {
       scanf("%d", &numScores); //read number of scores
       lengths[i] = numScores; //store number of scores as length for ith student
       studentscores[i] = (int *)malloc(numScores * sizeof(int)); //get space for storing marks for each student
       for(j = 0; j < numScores; j++)
           scanf("%d", &studentscores[i][j]); //read each score
   }

   printf("\nData read successfully....\n");
   for(i = 0; i < numStudents; i++) //print each student's data
   {
       printf("Student %d scores are : \n", i+1);
       for(j = 0; j < lengths[i]; j++)
           printf("%d ", studentscores[i][j]);
       printf("\n\n");
   }
  
   return 0;
}

------------------Screenshot main.c-----------

-/c/temp/main.c - Sublime Text (UNREGISTERED) 2:56 PM * main.c input.txt #include <stdio.h> #include <stdlib.h> #include <string.h> int main() { int **studentscores; //similar to two dimensional array for storing scores of all students int i, j, numStudents, numScores; scanf("%d", &numStudents); //read numnber of students 5 int *lengths; /* to store lengths of students marks araray (This is not required for this question) but i did it to print the entered data and verify if data is insert properly) */ studentscores = (int **)malloc(numStudents * sizeof(int *)); //allocate space for numStudents lengths = (int *)malloc(numStudents * sizeof(int)); //allocate space for numStudents sized array for(i = 0; i < numStudents; i++) //for each student 18 19 20 21 22 23 24 25 26 scanf("%d", &numScores); //read number of scores lengths[i] = numScores; //store number of scores as length for ith student studentscores[i] = (int *)malloc(numScores * sizeof(int)); //get space for storing marks for each student for(j = 0; j < numScores; j++) scanf("%d", &studentscores[i][j]); //read each score } printf("\nData read successfully....\n"); for(i = 0; i < numStudents; i++) //print each student's data printf("Student $d scores are : \n", i+1); for(j = 0; j < lengths[i]; j++) printf("d ", studentscores[i][j]); printf("\n\n"); } 33 34 35 36 return 0; } Line 27, Column 75 Tab Size: 4

------------------Output----------

/c/temp/input.txt - Sublime Text (UNREGISTERED) 2:52 PM 1 2 3 4 5 6 main.c. X input.txt 4 10 100 80 90 100 90 90 95 80 100 95 3 87 93 90 5 100 90 90 100 90 8 90 90 90 90 80 80 85 85 Line 6 Column 1 Tab Size: 4 Plain Text

2:52 PM vs@ubuntu: -/c/temp vs@ubuntu:-/c/temps gcc main.c vs@ubuntu:-/c/temp$ ./a.out < input.txt Data read successfully.... Student 1 scores are : 100 80 90 100 90 90 95 80 100 95 Student 2 scores are : 87 93 90 Student 3 scores are : 100 90 90 100 90 Student 4 scores are : 90 90 90 90 80 80 85 85 vs@ubuntu:-/c/temp$ I

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