Loop in basic C program - c

Question

I can't find and resolve the error in this code.
I want Parray and Tarray to be filled with an iteration of the equation in the loop. I tried both for and while loop, but it seems that only the first member of the array is given proper value, and that value is lost by the beginning of a new cycle.
#include <stdio.h>
#include <stdlib.h>
int main() {
int i;
int j;
float dt,P_init,t_init,t_end;
dt = 0.03125;
P_init = 30;
t_init = 0;
t_end = 30;
int n_steps = 0;
n_steps = t_end/(float)dt;
int Parray[n_steps+1];
int Tarray[n_steps+1];
for (i=0; i<n_steps+1; i++)
{
Parray[i]=0;
Tarray[i]=0;
}
Parray[0] = P_init;
Tarray[0] = t_init;
int x;
float P,t,dpdt;
x = 1;
while (x < n_steps+1)
{
float s,d;
P = Parray[x-1];
t = Tarray[x-1];
dpdt = 0.7 * P * (1-(P/750)) - 20;
s = P + (dt * dpdt);
Parray[x] = s;
d = t + dt;
Tarray[x] = d;
x++;
printf("%f %f ",s,d);
}
return(0);
}

Answer 1

#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int i, j, x;
float dt, P_init, t_init, t_end, P, t, dpdt;
dt = 0.03125;
P_init = 30;
t_init = 0;
t_end = 30;
int n_steps = 0;
n_steps = t_end / (float)dt;
// using float arrays
float Parray[n_steps+1];
float Tarray[n_steps+1];
for (i = 0; i < n_steps+1; i++)
Parray[i] = 0;
for (j = 0; j < n_steps+1; j++)
Tarray[j] = 0;
Parray[0] = P_init;
Tarray[0] = t_init;
for (x = 1; x < n_steps + 1; x++) {
float s , d;
P = Parray[x-1];
t = Tarray[x-1];
dpdt = 0.7 * P * (1 - (P / 750)) - 20;
s = P + (dt * dpdt);
Parray[x] = s;
d = t + dt;
Tarray[x] = d;
printf("%f %f\n", s, d);
}
return(0);
}
I changed the int arrarys to float arrays.
What do you actually calculate here?

Answer 2

This line
dpdt = 0.7 * P * (1-(P/750)) - 20;
It seems to have a float value, therefore the array must be float type, and ALL inputs you put in the array must be in FLOAT type.
Change this:
int Parray[n_steps+1];
int Tarray[n_steps+1];
to
float Parray[n_steps+1];
float Tarray[n_steps+1];
and
P_init = 30;
t_init = 0;
t_end = 30;
All of them should be 30.0, 0.0, 30.0
Don't forget this too:
Parray[i]=0;
Tarray[i]=0;
Change it to 0.0
In short, C is bad at differentiate between types, so if you declare a float array, all inputs must be x.0, not only x where x is an integer.