Answer to Question #336346 in C++ for Hanna

Question

Using Pointer

The students’ IDs and test answers are

stored in a file. The first entry in the file contains answers to the test in the form:

TFFTFFTTTTFFTFTFTFTT

Every other entry in the file is the student ID, followed by a blank, fol- lowed by the student’s responses. For example,

the entry:

ABC54301 TFTFTFTT TFTFTFFTTFT

indicates that the student ID is ABC54301 and the answer to question 1 is True, the answer to question 2 is False, and

so on. The exam has 20 questions, and the class has more than 150 students.

Each correct answer is awarded two points, each wrong answer gets one point deducted, and no answer gets zero

points.

Write a program that processes the test data. The output should be the student’s ID, followed by the answers, followed

by the test score, followed by the test grade. Assume the following grade scale: 90%–100%, A; 80%–89.99%, B; 70%–

79.99%, C; 60%–69.99%, D; and 0%–59.99%, F.

Answer 1

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

typedef struct {
	char name[20];
	char answer[21];
	int score;
	char grade;
} student;

int main(){
	student **array=NULL, **temp_array=NULL;
	student *curr_stud = NULL;
	FILE* file;
	
	char filename[200];
	char answer[20];
	double grade;
	int i, students_count=0, array_size=0;
	char result=0;
	
	while (true){
		printf("Enter filename (*.txt): ");
		scanf("%s", filename);
		file = fopen(filename, "r");
		if (file == NULL){ 
		   printf("Error opening file!\n");
		}
		else { 
	 		break; 
   		}
	}
	for (i = 0; i < 20; i++){
		fscanf(file, "%c", answer + i);
	}
	while (feof(file) == 0){
		if (students_count == array_size){
			array_size += 5;
			temp_array = (student**)malloc(array_size*sizeof(student*));
			
			for (i = 0; i < students_count; i++){
				temp_array[i] = array[i];
			}
			free(array); array = temp_array;
		}
		curr_stud=(student*)malloc(sizeof(student));
		if (fscanf(file, "%s", curr_stud->name) < 1) 
		   break;
		else{
			curr_stud->score = 0;
			fgetc(file);
			for (i = 0; i < 20; i++){
				curr_stud->answer[i] = fgetc(file);
				if (curr_stud->answer[i] != ' '){
					if (curr_stud->answer[i] == answer[i])
					   curr_stud->score += 2;
					else
						curr_stud->score -= 1;
				}
			}
			curr_stud->answer[20] = '\0';
			grade = curr_stud->score / (20 * 2.0);
			if (grade>=0.9) curr_stud->grade = 'A';
			else if (grade >= 0.8) curr_stud->grade = 'B';
			else if (grade >= 0.7) curr_stud->grade = 'C';
			else if (grade >= 0.6) curr_stud->grade = 'D';
			else curr_stud->grade = 'F';
			array[students_count++] = curr_stud;
		}
	}
	fclose(file);
	printf("   ID \t\t\t ANSWER \t     THE TEST SCORE   GRADE\n");
	for (i = 0; i < students_count; i++){
		printf("%s \t %s \t\t %d/40\t\t%c\n", array[i]->name,array[i]->answer, array[i]->score,
		array[i]->grade);
	}
	printf("Save result? (y\\n) ");
	getchar(); 
	scanf("%c", &result);
	if (result == 'y' || result == 'Y'){
		while (true){
			printf("Enter filename: ");
			scanf("%s", filename);
			file = fopen(filename, "w+");
			if (file == NULL){
			   printf("Error opening file!\n"); 
   			}
			else break;
		}
		for (i = 0; i < students_count; i++){
			fprintf(file, "%s - %s - %d - %c\n", array[i]->name, array[i]->answer,
			array[i]->score, array[i]->grade);
		}
		fclose(file);
	}
	for (i = 0; i < students_count; i++){
		free(array[i]);
	}
	free(array);
}