Question

#include <stdio.h>
#include <stdlib.h> // required for atoi
int main(void) {
    int i=0,n,num,filenum[100],pos;
    int c;
   char line[100]; //declaring string for storing data in the line of text
   FILE *fp; // declaring a FILE pointer
   fp=fopen("numbers.txt","r"); // open a text file for reading
   while(fgets(line, sizeof line, fp)!=NULL) {       // looping until end of the file
        filenum[i]=atoi(line); //converting data in the line to integer and storing it into array
       i++;
   }
   n=i;
   fclose(fp); //closing file
   printf("Enter a number: ");
   scanf("%d",&num);
   while(num!=EOF) //looping until user enters end of the file
   {
       pos=0;
       for(i=0;i<n;i++)
       {
           if(num==filenum[i])   //if num is equal to filenum[i]
           {
               pos=i+1;
           }
       }
       if(pos>0)
           printf("%d last appears in the file at position %d\n",num,pos);
       else
           printf("%d does not appear in the file\n",num);
       printf("Enter a number: ");
       scanf("%d",&num);  
              
   }
    return 0;
}

=====================================================

（does anyone can help me to change this program in C++ and add some comments)

numbers.txt:
10
23
43
5
12
23
9
8
10
1
16
9

you must to have all of following output:

Enter a number: 10
10 last appears in the file at position 9
Enter a number: 29
29 does not appear in the file
Enter a number: 9
9 last appears in the file at position 12
Enter a number:

Answer 1

Here is code:

#include <iostream>

#include <fstream>

using namespace std;

int main(void)

{

    int i = 0, n, num, filenum[100], pos;

    int c;

    char line[100]; //declaring string for storing data in the line of text

    ifstream fin("numbers.txt");

    int a;

    while (fin >> a) // read the number untill EOF

    {                   // looping until end of the file

        filenum[i] = a; //converting data in the line to integer and storing it into array

        i++;

    }

    n = i;

    fin.close();

    cout << "Enter a number: ";

    cin >> num;

    while (num != EOF) //looping until user enters end of the file

    {

        pos = 0;

        for (i = 0; i < n; i++)

        {

            if (num == filenum[i]) //if num is equal to filenum[i]

            {

                pos = i + 1;

            }

        }

        if (pos > 0)

            cout << num << " last appears in the file at position " << pos << "\n";

        else

            cout << num << " does not appear in the file\n";

        cout << "Enter a number: ";

        cin >> num;

    }

    return 0;

}

Output: