Table of Contents
Understanding the Peculiar Behavior of Zero-Prepended Numbers
Zero Digits and Octal Interpretation
Leading Zeros and Hexadecimal Interpretation
Octal Digits and Syntax Error
Conclusion
Home Backend Development C++ Why Do Zero-Prepended Numbers Behave Unexpectedly in C ?

Why Do Zero-Prepended Numbers Behave Unexpectedly in C ?

Dec 02, 2024 pm 10:43 PM

Why Do Zero-Prepended Numbers Behave Unexpectedly in C  ?

Understanding the Peculiar Behavior of Zero-Prepended Numbers

It is often observed that in certain programming languages like C , numerals prefixed with zero exhibit unexpected behavior. Let's delve into the specific scenarios you presented to comprehend these quirks.

Consider the following code excerpts:

int i = 07;     // i == 7
int i = 16;     // i == 16
int i = 00016;  // i == 14, why?
int i = 05016;  // i == 2574, wow )
int i = 08;     // compile error, compiler expects octal number...
Copy after login

Zero Digits and Octal Interpretation

In C , integer literals can be specified in decimal, octal, or hexadecimal bases. Zero-prepended integers are typically interpreted as octal literals, except when the literal begins with 0x or 0X, which indicates a hexadecimal base.

In your example, 00016 is interpreted as an octal literal, resulting in i == 14. Octal numbers represent values using the digits 0-7. The leading zeros do not affect the value of the literal.

Similarly, 05016 is also interpreted as an octal literal, which can be converted to decimal by multiplying each digit by the appropriate power of 8. This gives us i == 2574.

Leading Zeros and Hexadecimal Interpretation

However, if the literal begins with 0x or 0X, it is interpreted as a hexadecimal literal. Hexadecimal numbers represent values using the digits 0-9 and the letters A-F (or a-f).

In your example, 0x16 would be interpreted as a hexadecimal literal representing the value 22.

Octal Digits and Syntax Error

According to the C standard, 8 and 9 are not valid octal digits. Therefore, 08 is an invalid octal literal and results in a syntax error during compilation.

Conclusion

The quirks you observed with zero-prepended numbers stem from the specific rules for interpreting integer literals in C . By understanding these rules (namely, interpreting zero-prepended integers as octal literals unless specified otherwise), you can avoid errors and correctly handle integer values.

The above is the detailed content of Why Do Zero-Prepended Numbers Behave Unexpectedly in C ?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot Article Tags

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

What are the types of values ​​returned by c language functions? What determines the return value? What are the types of values ​​returned by c language functions? What determines the return value? Mar 03, 2025 pm 05:52 PM

What are the types of values ​​returned by c language functions? What determines the return value?

Gulc: C library built from scratch Gulc: C library built from scratch Mar 03, 2025 pm 05:46 PM

Gulc: C library built from scratch

C language function format letter case conversion steps C language function format letter case conversion steps Mar 03, 2025 pm 05:53 PM

C language function format letter case conversion steps

What are the definitions and calling rules of c language functions and what are the What are the definitions and calling rules of c language functions and what are the Mar 03, 2025 pm 05:53 PM

What are the definitions and calling rules of c language functions and what are the

Where is the return value of the c language function stored in memory? Where is the return value of the c language function stored in memory? Mar 03, 2025 pm 05:51 PM

Where is the return value of the c language function stored in memory?

distinct usage and phrase sharing distinct usage and phrase sharing Mar 03, 2025 pm 05:51 PM

distinct usage and phrase sharing

How do I use algorithms from the STL (sort, find, transform, etc.) efficiently? How do I use algorithms from the STL (sort, find, transform, etc.) efficiently? Mar 12, 2025 pm 04:52 PM

How do I use algorithms from the STL (sort, find, transform, etc.) efficiently?

How does the C   Standard Template Library (STL) work? How does the C Standard Template Library (STL) work? Mar 12, 2025 pm 04:50 PM

How does the C Standard Template Library (STL) work?

See all articles