How do I change the for loop to a while loop - c

Question

The for(t = 0; t < tmax …) located at the bottom of the program loop should be a while loop (e.g. while (s.distance > 0)) that runs while the altitude is greater than 0. Depending on what thrust the user selects, the tmax may or may not be enough time for the lander to land. In short I need to change the for loop to a while loop to speed the fuel consumption.
#include "stdio.h"
#include <math.h>
#include "string.h"
#include "ctype.h"
struct _State //different to shorten variable names
{
double mass;
double thrust;
double accel;
double velo;
double distance;
double fuel;
char gameMode; // variable for keeping track of selected mode (A - 65 - Autopilot / M - 77 - Manual)
};
typedef struct _State State;
double getThrust(State* s) // Accepts user input for thrust and validates it
{
printf("Input Thrust bellow. \n--> ");
scanf("%lf", &s->thrust);
if (s->thrust < 0)
{
return 0;
}
else if (s->thrust > 45000)
{
return 45000;
}
else
return s->thrust;
}
void Update(State* s, double t, double stepSize)
{
const double gMoon = -1.6;
//double mass = 9000;
//double fuel = 1800;
s->thrust = getThrust(s);
s->mass = s->mass - (s->thrust / 3000);
s->accel = (s->thrust / s->mass) + gMoon;
s->velo += s->accel * stepSize;
s->distance += s->velo * stepSize;
s->fuel = s->fuel - (s->thrust / 3000);
}
void manualControl(State* s) //manual controll function
{
printf("\nManual mode: on\n");
printf("-----------------\n\n");
if (s->distance == 0) // Sets height value to the initial height value for calculations
{
s->distance = 15000;
}
if (s->velo == 0) // Sets velocity value to the initial velocity value for calculations
{
s->velo = -325;
}
}
void autopilotControl(State* s) // Autopilot controll function
{
printf("\nAutopilot: on\n");
printf("-----------------\n\n");
}
void modeHandler(State* s) // mode controller. Calls appropriate function depending on the mode selected
{
if (s->gameMode == 65)
{
autopilotControl(s);
}
else if (s->gameMode == 77)
{
manualControl(s);
}
}
void modeSelect(State* s) // modeSelect allows user to pick the game mode and validates their input.
{
printf("--> ");
scanf("%c", &s->gameMode);
s->gameMode = toupper(s->gameMode);
if (s->gameMode == 65 || s->gameMode == 77)
{
modeHandler(s);
}
else
{
printf("\nInvalid input. Please try again!\n");
scanf("%c", &s->gameMode);
s->gameMode = toupper(s->gameMode);
modeSelect(s);
}
}
int main(void)
{
State s = { 9000,0,0,-325,15000,1800 };
printf("Welcome to the Lunar Lander simulation!\n\n");
printf("Your goal is to land the vehicle safely on the moon.\n");
printf("You will be provided with information about the lander\nbased on which you will have to make a decision about\nhow much force should be applied to slow the vehicle down.\n");
printf("-----------------------------------------------------------\n\n");
printf("Choose your game mode.\n(Type \"A\" for autopilot) or (\"M\" for manual mode)\n");
modeSelect(&s);
double t = 0;
double tmax = 150;
const double stepSize = 1;
FILE* f = fopen("lander.csv", "wt");
if (!f)
{
printf("Unable to open file.\n");
system("pause");
return 1;
}
for (t = 0; t < tmax; t++)
{
while (t < tmax)
{
fprintf(f, "%.2f,%.2f,%.2f,%.2f%.2f,\n", t, s.accel, s.velo, s.distance, s.fuel);
Update(&s, t, stepSize);
printf("Current height: %.2f m\n", s.distance);
printf("Current velocity: %.2f m/s\n", s.velo);
printf("Fuel left : %.2f kg\n", s.fuel);
printf("---------------------------\n\n");
}
}
system("pause");
}
Here the ouput:
Choose your game mode.
(Type "A" for autopilot) or ("M" for manual mode)
--> M
Manual mode: on
-----------------
Input Thrust bellow.
--> 20
Current height: 14673.40 m
Current velocity: -326.60 m/s
Fuel left : 1799.99 kg
---------------------------
Input Thrust bellow.
-->

Answer 1

It seems the fuel decrement can be defined within the Update(...) method. So, would not it be the case of defining something like the following suggestion?
// ...
int t = 0;
int tmax = 150;
// ...
while ((s.fuel > 0.0) && (t < tmax))
{
fprintf(f, "%.2f,%.2f,%.2f,%.2f%.2f,\n", t, s.accel, s.velo, s.distance, s.fuel);
Update(&s, t, stepSize);
printf("Current height: %.2f m\n", s.distance);
printf("Current velocity: %.2f m/s\n", s.velo);
printf("Fuel left : %.2f kg\n", s.fuel);
printf("---------------------------\n\n");
t++;
}
// ...