In the following program,
int * accepted_ids = (int *) malloc(sizeof(int)*N);
double * accepted_scores = (double *)malloc(sizeof(double)*N);
int * unaccepted_ids = (int *) malloc(sizeof(int)*N);
double * unaccepted_scores = (double *) malloc(sizeof(double)*N);
these memory allocations are creating arrays of size N for each of them, even though the number of needed elements are much lower than that of N.
Since the program is using a random number generator, we can't tell beforehand how much memory we need for each of them.
How can I solve this dilemma?
(max. 5 points)
A single dimension array SCORES stores scores of N university candidates they gained at high school. Indexes of elements of the array are the IDs of these candidates. The university accepts applications from candidates with the average score greater or equal to 4.0.Write a short program that will display:
• The list of accepted candidates with their ID number and their average score. • The list of unaccepted candidates with their ID numbers and their average score • The number of accepted and unaccepted candidates. • Results sorted in ascending order
The average scores should be calculated from a range <2,6> using random numbers generator. The total number of candidates should be passed to the program as command line parameter. Make your program sensible to the input of wrong parameters.
Using struct is not allowed.
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <errno.h>
// This function tests whether it is possible
// to convert a string into integer or not.
//
// This function is needed to check the
// input argument otherwise if you type
// C:\>myapp.exe abc
// your program will crash.
int is_integer(const char * s)
{
char * endptr;
int radix = 10;//decimal number system
// try to convert s to integer
strtol(s, &endptr, radix);
errno = 0;
// if this conditions are fullfilled,
// that means, s can't be converted
// to an integer.
if (endptr == s || *endptr != '\0')
{
// argument must be an integer value
return 0; // failure
}
if (errno == ERANGE)
{
// int argument out of range
return 0; // failure
}
return 1; //success
}
// This function is needed to convert
// a string to an integer value.
int string_to_integer(const char * s)
{
char * endptr;
int radix = 10;//decimal number system
// convert s to integer
return strtol(s, &endptr, radix);
}
// Generte a random number between M and N.
//
// This function is needed coz rand() can
// generate only integer values.
double round_between_m_to_n(double M, double N)
{
return M + (rand() / (RAND_MAX / (N - M)));
}
// This is Bubble sort algorithm
// This is implemented as a user-defined function,
// coz, you have to use this twice.
// First for accepted scores,
// then for unaccepted scores.
void sort(int * ids, double * scores, int count)
{
for (int i = 0; i < count; i++)
{
for (int j = 0; j < i; j++)
{
if (scores[i] < scores[j])
{
// Swap scores
double temp = scores[i];
scores[i] = scores[j];
scores[j] = temp;
// Swap ids
int temp2 = ids[i];
ids[i] = ids[j];
ids[j] = temp2;
}
}
}
}
// This function is to print ids and scores
// as a table.
// This is implemented as a user-defined function,
// coz, you have to use this twice.
// First for accepted scores,
// then for unaccepted scores.
void print(int * ids, double * scores, int count)
{
printf("id\tavg_score\n");
printf("-------------------\n");
for (int i = 0; i < count; i++)
{
printf("%i\t%.1f\n", ids[i], scores[i]);
}
}
int main(int argc, char ** argv)
{
// Program can proceed only if
// the # of arguments is exactly 2.
// The 1st arg is always app-name.
if (argc != 2)
{
printf("insufficient argument\n");
return EXIT_FAILURE;
}
int N = 0;
int accepted_scores_count = 0;
int unaccepted_scores_count = 0;
double acceptance_threshhold = 4.0;
if (!is_integer(argv[1]))
{
printf("incorrect argument type\n");
return EXIT_FAILURE;
}
else
{
N = string_to_integer(argv[1]);
printf("Total %d students\n", N);
}
// Pair of variables are needed to
// keep track of student-ids.
// Otherwise, you can't tell what id a
// student has when data are sorted.
int * accepted_ids = (int *)malloc(sizeof(int)*N);
double * accepted_scores = (double *)malloc(sizeof(double)*N);
int * unaccepted_ids = (int *)malloc(sizeof(int)*N);
double * unaccepted_scores = (double *)malloc(sizeof(double)*N);
//Initialize random seed.
//If you don't use this, rand() will generate
//same values each time you run the program.
srand(time(NULL));
// Simultaneously generate scores, ids, and
// store them is sepaerate arrays.
for (int i = 0; i < N; i++)
{
int id = i;
double score = round_between_m_to_n(2, 6);
// if the score is greater than or
// equal to 4.0...
if (score >= acceptance_threshhold)
{
accepted_ids[accepted_scores_count] = i;
accepted_scores[accepted_scores_count] = score;
accepted_scores_count++;
}
// ... otherwise they are unaccepted.
else
{
unaccepted_ids[unaccepted_scores_count] = i;
unaccepted_scores[unaccepted_scores_count] = score;
unaccepted_scores_count++;
}
}
// sort accepted students
sort(accepted_ids, accepted_scores, accepted_scores_count);
// sort unaccpeted students
sort(unaccepted_ids, unaccepted_scores, unaccepted_scores_count);
// print accepted students
printf("\naccepted students\n");
print(accepted_ids, accepted_scores, accepted_scores_count);
// print unaccepted students
printf("\nunaccepted students\n");
print(unaccepted_ids, unaccepted_scores, unaccepted_scores_count);
printf("\nEnd of program.\n");
free(accepted_ids);
free(accepted_scores);
free(unaccepted_ids);
free(unaccepted_scores);
return EXIT_SUCCESS;
}
