Double inequality while comparying three floating point numbers [duplicate]

Question

Can somebody tell me why the following does not work?(I mean no output)

if(0.0001<0.001<0.01)   
    cout<<"hi\n"<<endl;
output:    (blank)

While the following works:

if(0.0001<0.001 && 0.001<0.01)  
    cout<<"hi\n"<<endl;
  output:hi

Answer 1

Because there is no magical n-ary < operator in C++.

0.0001 < 0.001 < 0.01 

is parsed (since < is left-associative) as

(0.0001 < 0.001) < 0.01

and 0.0001 < 0.001 returns a value of type bool with value true. Now you have

true < 0.01

but according to the standard a true boolean has value 1 when converted to an integral type so you have

1 < 0.01

which is false.

Answer 2

When you are using condition like

(0.0001<0.001<0.01)

It will check first 0.0001<0.001 i.e. true which returns 1 and now condition become

( 1< 0.01 )

which is false so returns 0 that's why printing nothing.