ofstream out("file.txt");
char pwo;
pwo = (long double)p;
char pw[ ] = pwo;       //строка 14
out.write(pw, strlen(pw));
out.close();

char a[] = "ololo";
//тоже что и
//char a[6] = "ololo";

#include <fstream>
using namespace std;
void main()
{
    int num = 666;
    ofstream out("file.txt");
    char str[12];
    _itoa(num, str, 10);
    out.write(str, strlen(str));
    out.close();
}

#include <fstream>
using namespace std;
void main()
{
    double d = 5464.566;
    ofstream out("file.txt");
    char str[20];
    sprintf(str,"%0.02f",d);
    out.write(str, strlen(str));
    out.close();
}