A byte alignment problem encountered when porting applications to the ARM platform

A byte alignment problem encountered when porting applications to the ARM platform

Example:
Define a class as follows:
Class Example {
Public:
Example ();
PRIVATE:
Unsigned short C;
};

Since unsigned short is two bytes, this class occupies only two bytes on PC,
On the ARM platform, the class is 4 bytes because of the 4-byte alignment problem,
Therefore, when the pointer ++ is used in arm, a problem occurs. :)

The solution is to add the _ attribute _ (packed) parameter to the class when compiling the ARM platform program.

Test code:

# Include <stdio. h>
# Define platform_arm 0

Class Example
{
Public:
Unsigned short C;

# If platform_arm
}__ Attribute _ (packed ));
# Else
};
# Endif

Int main (void)
{
Example * exm = new example;

# If platform_arm
Printf ("On arm/N ");
# Else
Printf ("on PC/N ");
# Endif
Printf ("the sizeof class example is [% d], pointer is [% d]/n"
, Sizeof (example), sizeof (exm ));

Return 0;

}