index =0;
while(array1[index] && array2[index] != NULL)
{
    array1[index] = array1[index] ^ array2[index];
    array2[index] = array1[index] ^ array2[index];
    array1[index] = array1[index] ^ array2[index];
    index++;
}

for (index = 0; index < len; index++) {
    array1[index] ^= array2[index];
    array2[index] ^= array1[index];
    array1[index] ^= array2[index];
}

index = len;
while( index-- ) {
    array1[index] ^= array2[index];
    array2[index] ^= array1[index];
    array1[index] ^= array2[index];
}

while( len-- ) {
    array1[len] ^= array2[len];
    array2[len] ^= array1[len];
    array1[len] ^= array2[len];
}

index =0;
while(array1[index] != NULL  && array2[index] != NULL)
{
    array1[index] ^= array2[index];
    array1[index] ^= array2[index];
    array1[index] ^= array2[index];
    index++;
}