Why Are 08 and 09 Invalid Integer Literals in Java?

Why 08 is Invalid as an Integer Literal in Java

In Java, integer literals starting with 0 are interpreted as octal numbers (base 8). This can lead to confusion for numbers with multiple digits.

When 0 is followed by a single digit (except 8 or 9), the value is simply the numerical value of that digit. However, for numbers with more than one digit, the interpretation can be surprising.

For instance:

• 010 is interpreted as 8 (1 x 8 0)
• 024 is interpreted as 20 (2 x 8 4)

However, 08 and 09 are invalid integer literals in Java. This is because there are only 8 digits (0-7) in the octal system, so any number beginning with 08 or 09 would be out of range.

As a best practice, it's recommended to never start an integer literal with 0, unless you specifically intend to write zero itself. This will help avoid unexpected results due to octal interpretation.

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