Rounding Double Type Variables

Simple rules of conversion

In the last lesson, we saw how typecasting a double type variable to an int type variable only results in the decimal part of the number being dropped. This is likely not how you learned to convert decimal numbers to integers. The conversion you have likely studied follows these rules:

1. If the decimal part is less than .5: Round down, i.e., drop the decimal part.

2. If the decimal part is greater than or equal to .5: Round up, i.e., drop the decimal part and add $1$ if the number if positive, and subtract $1$ if negative.

Some examples are given below.

• Rounding $3.14$ gives $3$: $0.14$ is less than $0.5$, so $0.14$ is dropped

• Rounding $-1.25$ gives $-1$ ...