Ошибка с2664(не удается преобразовать аргумент n из type1 в type2) в 18 строке - C (СИ) (147703)

#include <iostream>
#include <fstream>
#include <string>
#define MAXFILENAME 20
#define MAXBUF 1024
#pragma warning(disable : 4996)
 
using namespace std;
void openfile(FILE *);
//int search();
 
int main(void)
{
    int amountLines = 0, fileLength = 0;
    char firstSimbol;
    char buf[MAXBUF];
    FILE *fp;
    [U][B]openfile(&fp)[/B][/U];
    while (!feof(fp))
    {
        buf[0] = '\0';
        fgets(buf, sizeof(buf), fp);
        fileLength = strlen(buf);
        if (fileLength > 0)
        {
            if (buf[fileLength - 1] == '\n')
            {
                buf[fileLength - 1] = '\0';
                fileLength--;
            }
            if (fileLength > 0)
            {
                if (buf[0] == buf[fileLength - 1])
                    amountLines++;
            }
        }
    }
    cout << "In the file " << amountLines << " string(s) that begin and end with the same character" << endl;
    system("pause");
    return 0;
}
void openfile(FILE **fp) 
{
    char filename[MAXFILENAME];
    cout << "Enter the name of file(example: name.txt): " << endl;
    cin >> filename;
    *fp = fopen(filename, "r");
    if (!fp)
    {
        cout << "Error file" << endl;
        exit(1);
    }
 
}