Project Home
Project Home		 Source Code
Source Code		 Documents
Documents		 Wiki
Wiki		 Discussion Forums
Discussions		 Project Information
Project Info
Core Development Tools/Discussion/General/More 4.2.1 question:/List of Posts
Forum Topic - More 4.2.1 question:: (4 Items)
   
Update
Mario Charest
09/19/2007 11:14 AM
post1398
More 4.2.1 question:   
extern void allo(char *);

void foo(void)
{

        char achar[10];
        unsigned char auchar[10];

        allo ( achar );
        allo ( auchar );

}

qcc -V4.2.1,gcc_ntox86 -w9 -funsigned-char try.c
will give: "pointer targets in passing argument 1 of 'allo' differ in signedness" even though -funsigned-char is 
specified!

- Mario
Ryan Mansfield(deleted)
09/19/2007 11:33 AM
post1400
Re: More 4.2.1 question:   
The C standard specifies (6.2.5/15 and note 35) that char, signed char and unsigned char are separate types. Regardless 
of which options you use, they are different types and the warnings are valid.

Regards,

Ryan Mansfield
dragon linux
09/19/2007 9:21 PM
post1441
Re: More 4.2.1 question:   
char is different with signed char?
Ryan Mansfield(deleted)
09/19/2007 11:36 PM
post1443
Re: More 4.2.1 question:   
> char is different with signed char?

char is implementation defined (usually defined by the processor ABI) to have the same range and representation as 
either signed or unsigned char. The -funsigned-char and -fsigned-char options control the behavior of char. 

However, as Note 35 of the C standard says, "Irrespective of the choice made, char is a separate type from the other two
 and is not compatible with either."

People should be aware that using the -funsigned-char -fsigned-char options can break ABI compatibility, and the options
 exist to be a  crutch for legacy code that assumes char to be either signed or char. Portable code should assume 
neither.

Regards,

Ryan Mansfield

Return


  A subsidiary of BlackBerry             All content ©2004-2013, QNX Software Systems