Thread: sum+= not working???

Code:

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


int main(int argc, char *argv[]) 
{
 int students;
 int *score;
 int i;
 int avg = 0, sum=0;
 
  printf ("enter student amount:\n");
  scanf ("%d", &students);
 score = (int*)malloc(sizeof(int)*students);
 
 for (i=0; i<students; i++){
  //scanf ("%d", &score[i])
  scanf ("%d", score+i);
 }
 
 for (i=0; i<students; i++){
  printf ("student %d: %d\n", i+1, score[i]);
 }
 
 sum += score[i];
 printf ("sum: %d\n", sum);
 avg = sum/ students;
 printf ("Avg = %d", avg);
 
 free(score);
 
 system("pause"); 
 return 0;
}

this is my code, can anyone help me? I'm using the sum+= score [i], it should work since i can add the array part right?

You don't cast the malloc call, and you didn't increment the sum in a loop.

Code:

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




int main(int argc, char *argv[])
{
 int students;
 int *score;
 int i;
 int sum=0;
 float avg = 0;


  printf ("enter student amount:\n");
  scanf ("%d", &students);
 score = malloc(sizeof(*score)*students);


 printf ("enter scores:\n");
 for (i=0; i<students; i++){
  //scanf ("%d", &score[i])
  scanf ("%d", score+i);
 }


 for (i=0; i<students; i++){
  printf ("student %d: %d\n", i+1, score[i]);
  sum += score[i];
 }


 printf ("sum: %d\n", sum);
 avg = (float)sum / students;
 printf ("Avg = %f\n", avg);


 free(score);


 system("pause");
 return 0;
}

could you please explain what you meant by the malloc part? and why would I increment the sum in the loop, I want the sum to be calculated after each student has entered their score. Thx!

You were accessing a part of the array you didn't allocate earlier was the first problem. Your variable i was equal to students and your max index was students - 1.

If you want to do a sum you have to walk through each index of the array which is why you want to increment the sum in the loop.

Thanks guys, the problem is solved, sum is now in the loop, works perfectly now. Thx!