Is 'bool' 1 or 2 bytes in C Builder? I'm getting conflicting results-CodePudding

The following code returns a bool in the AL CPU register:

bool Exiting;
bool WINAPI IsExiting()
{
   return Exiting;
}

which compiles to:

00488BA4 55               push ebp
00488BA5 8BEC             mov ebp,esp
00488BA7 6843475300       push $00534743
00488BAC 83C4F4           add esp,-$0c
00488BAF C745F8CC8B4800   mov [ebp-$08],$00488bcc
00488BB6 C745F001000000   mov [ebp-$10],$00000001
00488BBD A0B0C0A900       mov al,[$00a9c0b0] <------------------ AL has the result
00488BC2 896DFC           mov [ebp-$04],ebp
00488BC5 896DFC           mov [ebp-$04],ebp
00488BC8 8BE5             mov esp,ebp
00488BCA 5D               pop ebp
00488BCB C3               ret

But I've found when calling it:

if (!IsExiting()) {
  task1
}
if (!IsExiting()) {
  task2
}

task1 works, task2 doesn't always. The reason is:

if (!IsExiting())

compiles down to:

0040419E E8014A0800       call IsExiting()
004041A3 6685C0           test ax,ax     <------ bool is stored in AL, but test is on AX
004041A6 755C             jnz $00404204

Am I missing something? AX is 16 bits, AL is 8 bits.

Is this a compiler error, or am I being stupid somehow?

CodePudding user response：

Turns out, I had a difference in the function declaration. For reasons I was not able to include the header file of the IsExiting, which correctly declared it as

bool WINAPI IsExiting();

But the function was declared (incorrectly) locally in the calling file as

short WINAPI IsExiting();

I was being stupid somehow. (funny how by asking the question on StackOverflow, you are then able to find the answer).

CodePudding user response：

Short answer. Stop using WINAPI in your functions.

Long answer. You should avoid using WINAPI in your functions. You may use a similar macro only for functions of a public API and should use another than WINAPI name. The calling convention for private functions should be set up in the project/compiler settings.