0.4 - 0.3 = = 0.1 은 true??false

주의 하 셨 나 요?
 
이곳 의 연산 결 과 는 false 입 니 다.
 
이거 루비 에서 설명 한 거 예요.하하, 보 았 군.
 

Float objects have plenty of precision and can approximate 0.1 very well, 
but the fact that this number cannot be represented exactly leads to problems. 
Consider the following simple Ruby expression:

0.4 - 0.3 == 0.1    # Evaluates to false in most implementations

Because of rounding error, the difference between the approximations of 0.4 and 0.3 is 
not quite the same as the approximation of 0.1. This problem is not specific to Ruby: C, 
Java,JavaScript, and all languages that use IEEE-754 floating-point numbers suffer 
from it as well.