Binary representation of a char array

Question

I have a union, that is 8 fields of uint8, 2 fields of int32, or one int64.

I am trying to save an array of 8 values there: 0, 0, 0, 1, 0, 0, 0, 1

There is a bug in the software that I am trying to solve unfortunately, I don't understand the binary representation of this array.

My union:

union {
    uint8_t u08[8];
    uint32_t u32[2];
    uint64_t u64;
} data;

My debugger output:

Name : u08
Details:"\0\0\0\001\0\0\0\001"
Default:0x4001e6a0 <ucHeap+66948>
Decimal:1073866400
Hex:0x4001e6a0
Binary:1000000000000011110011010100000
Octal:010000363240

Name : u32
Details:{1, 1}
Default:0x4001e6a0 <ucHeap+66948>
Decimal:1073866400
Hex:0x4001e6a0
Binary:1000000000000011110011010100000
Octal:010000363240

Name : u64
Details:4294967297
Default:4294967297
Decimal:4294967297
Hex:0x100000001
Binary:100000000000000000000000000000001
Octal:040000000001

My questions are:

1. why does a u64 have a different value than the others? as far as I understand, c saves space only for one variable of a union to store the value.
2. what does this binary representation of the uint8 array mean? Even if it was ASCII (which it isn't, as I am sending direct values, not chars), then '0' is 110000 and '1' is 110001

I'm using MPC5748G from NXP with S32DS (eclipse based IDE) for the debugging.

Answer 1

What you see is not you think you see. Everything is correct there. u08 & u32 are arrays. u64 is an integer value and the debugger displays different information

Name : u08
Details:"\0\0\0\001\0\0\0\001"    -- actual values stored in the array
Default:0x4001e6a0 <ucHeap+66948> -- address of the array u08
Decimal:1073866400                -- same address in different bases
Hex:0x4001e6a0
Binary:1000000000000011110011010100000
Octal:010000363240

Name : u32
Details:{1, 1}                     -- actual values stored in the array
Default:0x4001e6a0 <ucHeap+66948>  -- address of the array u32
Decimal:1073866400                 -- same address in different bases
Hex:0x4001e6a0
Binary:1000000000000011110011010100000
Octal:010000363240

Name : u64
Details:4294967297                 -- value stored un the u64 integer
Default:4294967297                 -- same value in different bases
Decimal:4294967297
Hex:0x100000001
Binary:100000000000000000000000000000001
Octal:040000000001

{0, 0, 0, 1, 0, 0, 0, 1} is in big endian representation:

• 0x00000001 ( 1 ) in u32
• 0x0000000100000001 ( 0x100000001 without zeroes) in u64

if you want to see the same information for all the members you need to make the last member an array:

union {
    uint8_t u08[8];
    uint32_t u32[2];
    uint64_t u64[1];
} data;