Byte Alignment in C structure

[ravikandagal1]

Hello ,

I had a program which was crashing in HP IA 64 bit machine.
My program is configured for 4 byte alignment( #pragma pack(4)).
The same program didnt crash when configured for 8 byte alignment( #pragma pack(8))
Program was like this :

typedef enum comp
{
comp1=-1,
comp2,
comp3=0xFFFFFFF

}
typedef struct str1
{
comp nComp;
FunPtr nfunptr1;(Function pointer )
FunPtr nfunptr2;(Function pointer )

}str;

Structure str has a initialization as below :

str gStr[10]
= {
{comp(-1),mfunptr1,0L},
{comp(-1),mfunptr1,0L},
..
..
{comp(-1),mfunptr1,0L},
{comp(-1),mfunptr1,0L}

}

The above program used to crash.

But when i changed the code as below it didnt crash.
But i didnt understand why ?

typedef struct str1
{

FunPtr nfunptr1;/*Function pointer*/
FunPtr nfunptr2;/*Function pointer*/
comp nComp;
unsigned int PaddByte;/*Padding 4 byte*/

}str;



str gStr[10]
= {
{mfunptr1,0L},
{0L,mfunptr1,comp(-1)},
..
..
{0L,mfunptr1,comp(-1)},
{0L,mfunptr1,comp(-1)}

}


Please help me understand this ......

[vvadan]

please do not re-post the same question

Ref: http://www.cplusplus.com/forum/unices/31442/