变量将小数转换为整数

Question

If I explicitly convert a decimal value to an integer value, will the decimal values simply be truncated or will the value be rounded off?

for example: if d = 8.89

int i = (int)d;

Will i be 8 or 9 ??

Answer 1

It will truncate to 8.

If you would like it to round, you can use something like:

int i = (int)Math.round(d);

Answer 2

From the C# Language Specification V5 ¹ §6.2.1 Explicit numeric conversions :

For a conversion from decimal to an integral type, the source value is rounded towards zero to the nearest integral value, and this integral value becomes the result of the conversion. If the resulting integral value is outside the range of the destination type, a System.OverflowException is thrown.

Other languages/platforms which have a type like decimal may have different rules: in each and every case you need to check the rules specific to that language/platform. Eg. rules for T/SQL are different :

By default, SQL Server uses rounding when converting a number to a decimal or numeric value with a lower precision and scale. However, if the SET ARITHABORT option is ON, SQL Server raises an error when overflow occurs. Loss of only precision and scale is not sufficient to raise an error.

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¹ As included with Visual Studio 2013.