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Q35037: INFO: How C Interprets Integer Constants with Leading Zeroes

Article: Q35037
Product(s): Microsoft C Compiler
Version(s): 1.0,1.5,1.51,1.52,2.0,2.1,4.0,5.0,6.0
Operating System(s): 
Keyword(s): kbLangC kbVC100 kbVC150 kbVC151 kbVC152 kbVC200 kbVC210 kbVC400 kbVC500 kbVC600
Last Modified: 12-DEC-2001

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The information in this article applies to:

- Microsoft Visual C++, versions 1.0, 1.5, 1.51, 1.52, 2.0, 2.1, 4.0 
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SUMMARY
=======

Two similar assignment statements produce very different results when the
application prints values assigned. For example:

  a = 20;
  printf("%d", a);   /* this prints "20" */ 
  a = 020;
  printf("%d", a);   /* but this prints "16" */ 

Any number with a leading "0" (zero) is interpreted to be an octal number (base
8). Remove the leading zero from the decimal number.

MORE INFORMATION
================

All character constants of the form "\<o>", "\<o><o>",
"\<o><o><o>", (where <o> is a digit) and their string
equivalents are specified in octal as well. For example, \33 and \033 each
specify the ESC character (decimal 27, hexadecimal 1B). To specify a character
constant in hexadecimal, use "\x<h><h>", where <h> is a
hexadecimal digit. C does not provide a method to specify a decimal number in a
character constant; you can use a decimal integer constant instead (for example,
ch = 27).

Additional query words:

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Keywords          : kbLangC kbVC100 kbVC150 kbVC151 kbVC152 kbVC200 kbVC210 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbvc150 kbvc100 kbVC500 kbVC600 kbVC151 kbVC200 kbVC210 kbVC32bitSearch kbVC152 kbVC500Search
Version           : :1.0,1.5,1.51,1.52,2.0,2.1,4.0,5.0,6.0
Issue type        : kbinfo

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