hello

i want to calculate volume of Tank, but i have this error

return-statement with a value, in function returning ‘void’ [-fpermissive]

return v=(s * l) / 1000.0;

my function

```
long duration;
int h;
const double l = 26.0;
const double r = 6.0;
double s = 0;
double v = 0;
h= duration*0.034/2;
if ((h >= 0) && (h < r))
s = r * r * atan(sqrt(2 * r * h - h * h) / (r - h)) - (r - h) * sqrt(2 * r * h - h * h);
else if ((h >= 0) && (h == r))
s = M_PI * r * r / 2;
else if ((r >= 0) && (r < h) && (h <= 2 * r))
s = M_PI * r * r + (h - r) * sqrt(2 * r * h - h * h) - r * r * atan(sqrt(2 * r * h - h * h) / (h - r));
return v=(s * l) / 1000.0;
Serial.println(s);
```

Moderator edit:

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tags added.