realloc function don't save new elements with new values in c - c

Question

function gets an array of grades and changes the amount of grades if there are less elements than before the function will delete those elements
for example: before: I entered in another function 3 grades: 100, 90, 80.
after: In this function it asked me to enter new amount, and I entered, and then entered it's grade, 70.
after I return it to the main and sending the array, grades, to a function which prints the array and it's stays with 3 elements, 100, 90, 80.
please help me i tried a lot of time and didn't succeed.
void changeNumOfGrades(int* grades, int size)
{
int numOfGrades = 0;
int i = 0;
do
{
if (i > ONE_ITERATION)
{
printf("Please enter positive number...\n");
}
printf("How many elements would you like? ");
scanf("%d", &numOfGrades);
i += 1;
} while (numOfGrades < 0);
grades = realloc(grades, numOfGrades*sizeof(int));
if (!grades)
{
printf("Unsuccessful realloc");
//There is no need to release memory because the realloc is for the same pointer.
}
if (numOfGrades > size)
{
printf("You have more grades than before,\nPlease enter their grades: \n");
int newGrade = 0;
//int newNumOfGrades = numOfGrades - size;
int i = 0;
for (i = size + 1; i <= numOfGrades; i++)
{
printf("Enter grade number %d: ", i);
scanf("%d", &newGrade);
*(grades + i - 1) = newGrade;
printf("hey %d", *(grades + 1));
}
}
}

Answer 1

In order for you to reallocate grades, you need to pass as **grades.
For test reasons, I have changed size to get the new allocation size, so you can print the array after the changeNumOfGrades
void changeNumOfGrades(int** grades, int *size/*get new size*/)
{
int numOfGrades = 0;
int i = 0;
do
{
if (i > ONE_ITERATION)
{
printf("Please enter positive number...\n");
}
printf("How many elements would you like? ");
scanf("%d", &numOfGrades);
i ++;
} while (numOfGrades < 0);
printf("%d",numOfGrades);
*grades = realloc(*grades, numOfGrades*sizeof(int));/*realloc **grade */
if (!grades)
{
printf("Unsuccessful realloc");
//There is no need to release memory because the realloc is for the same pointer.
}
printf("...\n");
if (numOfGrades > *size)
{
printf("You have more grades than before,\nPlease enter their grades: \n");
int newGrade = 0;
//int newNumOfGrades = numOfGrades - size;
int i = 0;
for (i = *size + 1; i <= numOfGrades; i++)
{
printf("Enter grade number %d: ", i);
scanf("%d", &newGrade);
*(*grades + i - 1) = newGrade;
//printf("hey %d", *(grades + 1));
}
}
*size = numOfGrades;/*get new size allocated*/
}
void main()
{
int numOfInts;
int *grades ;
grades = malloc(3*sizeof(int));
memset(grades,0,sizeof(int)*3);
grades[0]=100;
grades[1]=80;
grades[2]=20;
numOfInts = 3;/*initialize 3 items*/
changeNumOfGrades(&grades,&numOfInts);
printf("\n\n");
for (int i=0;i<numOfInts;i++)
{
printf("%d\n",grades[i]);
}
free(grades);
}