Помогите С++ с цикла for нужно сделать while цикл и do while цикл точнее у меня вышла только с циклом for

#include <iostream>
using namespace std;
double real(const char* msg) {
cout << msg;
double value;
cin >> value;
cin.ignore(cin.rdbuf()->in_avail());
return value;
}
int main() {
const int x = 4;
const int h = 8;
auto a = real("a: ");
auto n = real("n: ");
auto d = 0.0;
while (!d) d = real("d: ");
auto m = 1.0;
int j = 0;
while (++j <= x) m *= n * n * (j + x);
auto t = m / pow(d, 3);
auto s = 0.0;
int i = 0;
while (++i <= h) s += i + a;
auto y = t + s;
cout << "y: " << y << '\n';
system("pause > nul");
}

#include <iostream>
using namespace std;
double real(const char* msg) {
cout << msg;
double value;
cin >> value;
cin.ignore(cin.rdbuf()->in_avail());
return value;
}
int main() {
const int x = 4;
const int h = 8;
auto a = real("a: ");
auto n = real("n: ");
double d;
do d = real("d: "); while (!d);
auto m = 1.0;
int j = 1;
do m *= n * n * (j + x); while (++j <= x);
auto t = m / pow(d, 3);
auto s = 0.0;
int i = 1;
do s += i + a; while (++i <= h);
auto y = t + s;
cout << "y: " << y << '\n';
system("pause > nul");
}

#include <iostream>
using namespace std;
double real(const char* msg) {
cout << msg;
double value;
cin >> value;
cin.ignore(cin.rdbuf()->in_avail());
return value;
}
int main() {
const int x = 4;
const int h = 8;
auto a = real("a: ");
auto n = real("n: ");
double d;
for (d = 0.0; !d; d = real("d: "));
auto m = 1.0;
for (int j = 1; j <= x; ++j) m *= n * n * (j + x);
auto t = m / pow(d, 3);
auto s = 0.0;
for (int i = 1; i <= h; ++i) s += i + a;
auto y = t + s;
cout << "y: " << y << '\n';
system("pause > nul");
}