CODEWITHSUNDEEP
cfloating-pointdouble
IainGM
IainGM

Reputation: 565

Why is this simple piece of code not working?

I am trying to get a floating variable accurate to just 3 decimal points for a comparison calculation. I am trying the method below, but it doesn't work. I can't see why not, so please can someone tell me where I am going wrong.

Output from this code is b = 10000.050617, bb = 10000050 and fbb = 10000.000. I want fbb to be 10000.050.

int bb; double m,n,p,q,b,t,u,fbb;

m=24.161, n=57.695, p=67.092, q=148.011;
t=p-m; u=q-n;
b=t*t+u*u; bb=b*1000; fbb=bb/1000;

printf("b=%.6lf,bb=%i,fbb=%.3lf\n",b,bb,fbb);

return 0;

Upvotes: 0

Views: 163

Answers (5)

Kanwaljit Singh
Kanwaljit Singh

Reputation: 4387

When you perform

fbb = bb/1000;

It treats operation as int/int and returns an int. its demotion of value.

Also take long bb; instead of int as int has value 32767 as its high value.

Try

fbb = bb/1000.000;

or 

fbb = (double)bb/1000;

Upvotes: 1

Yu Hao
Yu Hao

Reputation: 122493

bb is an int, so bb / 1000 will follow the integer division. Change either or both operand to a double. The simplest way is:

fbb = bb / 1000.0;       //type of 1000.0 is double

or 

fbb = (double)bb / 1000

Upvotes: 5

Oleg Olivson
Oleg Olivson

Reputation: 499

Use 

fbb=(double)bb/1000;

bb is integer and result is integer, and then converted to double

Upvotes: 0

Curd
Curd

Reputation: 12457

bb is int. So bb/1000 is doing a int division, which results again in an int = 1000 (no decimals). That int value is cast to a double.

Upvotes: 0

Swanand
Swanand

Reputation: 4115

When you perform

 fbb = bb/1000;

It treats operation as int/int and returns an int

Try 

fbb = ((double)bb)/1000.000;

It will be treated as (double)/(double) and return a double.

Upvotes: 5

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