Write Array in Structure

Question

I am very beginner in C. I have the following structure

typedef struct
{
    zuint8                      u8ZCLVersion;

 #ifdef CLD_BAS_ATTR_LOCATION_DESCRIPTION
    tsZCL_CharacterString       sLocationDescription;
    uint8                       au8LocationDescription[16];
 #endif

 #ifdef CLD_BAS_ATTR_PHYSICAL_ENVIRONMENT
    zenum8                      u8PhysicalEnvironment;
 #endif

 #ifdef CLD_BAS_ATTR_DEVICE_ENABLED
    zbool                       bDeviceEnabled;
 #endif
} tsCLD_Basic;

now i want to set au8LocationDescription[16] field. And I am using this piece of code.

tsCLD_Basic sCombined;
sCombined.au8LocationDescription[16] = {0x42,0x65,0x64,0x20,0x52,0x6f,0x6f,0x6d};

but its shows error error: expected expression before '{' token

how could I write the values..???

Answer 1

sCombined.au8LocationDescription[16] = {0x42,0x65,0x64,0x20,0x52,0x6f,0x6f,0x6d};

What this line tells the compiler to do is to assign {0x42,0x65,0x64,0x20,0x52,0x6f,0x6f,0x6d} to the sixteenth element of array au8LocationDescription.

It won't work. First, au8LocationDescription[16] is not a valid location. Writing anything there results in undefined behavior. Your array has only 16 elements, so you are only allowed to used indices from 0 to 15. And it doesn't even represent an array, its an int.

But since you're trying to fill up the array with some values, that is irrelevant. You might try

 sCombined.au8LocationDescription = {0x42,0x65,0x64,0x20,0x52,0x6f,0x6f,0x6d};

but that won't work either. You can't assign to arrays that way. This trick is only allowed in initialization.

What remains is assigning the elements of the array one-by-one. But if you want to save LOC's, you can do something along these lines:

static uint8 values[] = {0x42,0x65,0x64,0x20,0x52,0x6f,0x6f,0x6d};
memcpy(sCombined.au8LocationDescription, values, sizeof(values));

Answer 2

As the comment of Als says, what you are trying to do is not possible. You will need to assign each array element separately like this

    sCombined.au8LocationDescription[0] = 0x42;
    sCombined.au8LocationDescription[1] = 0x65;
    ...

and so on until each element is has the value you want.