Microsoft KB Archive/35037

Knowledge Base

INFO: How C Interprets Integer Constants with Leading Zeroes

Article ID: 35037

Article Last Modified on 12/11/2003

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APPLIES TO

• Microsoft Visual C++ 1.0 Professional Edition
• Microsoft Visual C++ 1.5 Professional Edition
• Microsoft Visual C++ 1.51
• Microsoft Visual C++ 1.52 Professional Edition
• Microsoft Visual C++ 2.0 Professional Edition
• Microsoft Visual C++ 2.1
• Microsoft Visual C++ 4.0 Standard Edition
• Microsoft Visual C++ 5.0 Enterprise Edition
• Microsoft Visual C++ 6.0 Enterprise Edition
• Microsoft Visual C++ 5.0 Professional Edition
• Microsoft Visual C++ 6.0 Professional Edition
• Microsoft Visual C++ 6.0 Standard Edition

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This article was previously published under Q35037

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).

Keywords: kbinfo kblangc KB35037

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