float

Do anyone have an idea of this behaviour???

Code:

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cout << Density << "\n"; //this print 0.13
float f = Density*100;
slider1->setValue(f); //this set slider1 to 12!!!! why????

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Code:

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float f = 0.13*100;
slider1->setValue(f);  //this set slider1 to 13

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Probably due to limited precision of float and implicit floor casting to int.

Did you ever try to compare float values ? :)
Check this out:

Code:

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#include <iostream>
 
int main(){
  float n = 0.99;
  while(n!=0.09){
    std::cout << n << std::endl;
    n-=0.01;
  }
  return 0;
}

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Try this to make your app work:

Code:

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float f = Density*100;
slider1->setValue((int)(0.5+f));

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The second line is equivalent to

Code:

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slider1->setValue(round(f));

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but Windows doesn't know how to round(), so a hack like (int)(0.5+f) is needed.

Because in the fallow code line:

Code:

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float f = Density*100;

---

and

Code:

---

float f = 0.13*100;

---

the number "100" in implicity cast to a float and this conversion could lead to a precision lost.

Try to use:

Code:

---

float f = Density*100.0;

---

and

Code:

---

float f = 0.13*100.0;

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Quote:

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Originally Posted by Zatraz

Because in the fallow code line:

Code:

---

float f = Density*100;

---

and

Code:

---

float f = 0.13*100;

---

the number "100" in implicity cast to a float and this conversion could lead to a precision lost.

Try to use:

Code:

---

float f = Density*100.0;

---

and

Code:

---

float f = 0.13*100.0;

---

---

sorry but your example doesn't solve the problem......

Try mine, it should work just fine.

Quote:

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Originally Posted by wysota

Try mine, it should work just fine.

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yes I just use it! I thanked you for this......