New types of C99 syntax _bool

The new Boolean type syntax for _bool is added in the C99 syntax, as shown in the following example:

1#include <stdio.h>2#include <stdlib.h>3 4 intMainintargcChar**argv)5 {6 _bool B;7b =0;8printf"%d\n", b);9b =1;Tenprintf"%d\n", b); Oneb =3; Aprintf"%d\n", b); -b =4; -printf"%d\n", b); theprintf"%d\n",sizeof(b)); -  -printf"%d\n", b); - GetChar (); +     return 0; -}

The results are as follows:

The disassembly results are as follows:

_bool B; b=0; 0119406E movbyteptr [b],0printf ("%d\n", b);01194072movzx eax,byteptr [b]01194076mov esi,esp01194078push EAX01194079Push 1195858h 0119407E call DWORD ptr ds:[1199110h]01194084Add ESP,8  01194087CMP Esi,esp01194089Call __rtc_checkesp (01191136h) b=1; 0119408E movbyteptr [b],1printf ("%d\n", b);01194092movzx eax,byteptr [b] printf ("%d\n", b);01194096mov esi,esp01194098push EAX01194099Push 1195858h 0119409E call DWORD ptr ds:[1199110h] 011940a4 add ESP,8011940A7 cmp esi,esp 011940a9 call __RTC_CHECKESP (01191136h) b=3; 011940AE mov eax,3011940b3 Test eax,eax 011940b5 jne main+73h (011940C3H) 011940b7 mov dword ptr [EBP-0D0H],0011940C1 jmp Main+7Dh (011940CDh) 011940C3 mov dword ptr [EBP-0D0H],1011940CD mov cl,bytePTR [ebp-0d0h] 011940D3 movbyteptr [b],cl printf ("%d\n", b); 011940d6 movzx eax,byteptr [b] 011940DA mov esi,esp 011940DC push eax printf ("%d\n", b); 011940DD push 1195858h 011940E2 call DWORD ptr ds:[1199110h] 011940E8 add ESP,8011940EB cmp esi,esp 011940ED call __RTC_CHECKESP (01191136h) b=4; 011940F2 mov eax,4011940f7 Test eax,eax 011940f9 jne main+0b7h (01194107h) 011940FB mov dword ptr [EBP-0D0H],0  01194105JMP main+0c1h (01194111h)01194107mov dword ptr [ebp-0d0h],1  01194111MOV cl,bytePTR [ebp-0d0h]01194117movbyteptr [b],cl printf ("%d\n", b); 0119411A movzx eax,byteptr [b] 0119411E mov esi,esp01194120push EAX01194121Push 1195858h01194126Call dword ptr ds:[1199110h] 0119412C add ESP,80119412F CMP Esi,esp01194131Call __rtc_checkesp (01191136h) printf ("%d\n",sizeof(b));01194136mov esi,esp01194138Push10119413A push 1195858h 0119413F call DWORD ptr ds:[1199110h]01194145Add ESP,8  01194148CMP esi,esp 0119414A call __RTC_CHECKESP (01191136h)

As can be seen from the results, not 0 is 1;

The results from the disassembly can also be seen

    4 ; 011940f2  mov         eax,4  011940f7  test        eax,eax  011940f9  jne         main+0b7h (01194107h)  011940FB  mov         dword ptr [EBP-0d0h],0  01194105  JMP         main+0c1h (01194111h)  01194107  mov         dword ptr [ebp-0d0h],1   01194111  mov         cl,byte ptr [ebp-0d0h]  01194117   mov         byte ptr [b],cl  

b = 4

MOV eax,4

The Prime Minister 4 gave eax;

Test Eax,eax

As long as it's not 0, it's 1.

This is the internal mechanism of the _bool type.

By:ecn14

New types of C99 syntax _bool