Modify the grade book program below to use a custom struct to hold the student's ID number and the percentage score for each item in the grade book. The program should accept the entry of ID numbers and percentage grades (0100) until the user signals that he or she is done entering grades. The program should then print out the ID numbers and grades entered by the user, sorted by ID number. be sure provide comments in the C code.

#include "stdio.h"

int main(void)

{

//initialize array

int arr[100];

//initialize variables

int i=0, j=0, n=0;

//infinite loop which will stop when user enters -1

while(n != -1)

{

printf("Enter percentage grade(0-100). Enter -1 to stop: ");

//read grade

scanf("%d",&n);

//if user entered grade is not -1

if(n != -1)

{

//save it to array

arr[i++] = n;

}

//if user entered -1, then exit this loop

else

{

break;

}

}

printf(" The grades are: ");

//loop which will iterate till no:of user entered grades

for(j=0; j

{

//print the grade

printf("%d ",arr[j]);

}

return 0;

}