A weird number was outputted

Question

Why it appear a strange number(5.3649e-0.7)during subtraction for two float numbers(in c++)?
The number should be zero but it didn't.
And the total sum was not effected at all.
Could anyone tell me why it happens?

Answer 1

we can tell what its wrong, if you show the code.

But I asume that one variable wasn't assigned and had garbage default value.

Answer 2

That is because binary representation of floating point.

https://en.wikipedia.org/wiki/Floating_point

You will have to check a library, or truncate the value to 2 decimals, that mights work if you get them to string and then show index 0, 1 (point), 2 , and 3

Answer 3

Indeed, You are adding stuff to a not initialized var.

float sum = 0;

Answer 4

Here's the code.
#include <iostream>
using namespace std;

int main()
{float sum;
float y=2.8;
for(int x=0;x<14;x++){
sum+=y;
cout<<y<<endl;
y-=0.4;}
cout<<sum;
return 0;
}

Answer 5

I think the variable sum isn't initialised so it has some garbage value. I think so!!

Answer 6

@Nahuel Ovejero thx:)
But the problem happened on the var y which is initialized. I'm really curious about that. :)

Answer 7

gotit!!Thx :)