Identify machine is little or big endian

int a = 0x01346283;

    This is 32 bit machine. 

int data type is 4 byte

in memory it is allocated as below

in little endian

1001    1002    1003    1004

83        62        34         01   

in big endian

1001    1002    1003    1004

01        34         62        83

int main()

{

    int a = 1;

    char *b = (char *)&a;

    if(*b)

        then its little endian

}

To convert one endian to other, write macro which does left shift each byte and OR it

for ex:

int x = 0x12345678

from little endian to big endian

78 << 0 | 56 << 8 | 34 << 16 | 12 << 24

from big endian to little endina

12 << 0 | 34 << 8 | 56 << 16 | 78 << 24