字符串末尾的“$”标记是否有特殊含义？

请参考我在某个c程序中看到的代码：

#define _BUILD_DATE     "2010/05/03$" 
#define _BUILD_TIME     "10:46:42$"
#define _BUILD_GUEST    "Intel$"
#define _BUILD_BOARD    "B0$"
#define _BUILD_CODEVER  "2.00$"

const unsigned char SIGN_DATE[] = {_BUILD_DATE};
const unsigned char SIGN_TIME[] = {_BUILD_TIME};
const unsigned char SIGN_GUST[] = {_BUILD_GUEST};
const unsigned char SIGN_PCBV[] = {_BUILD_BOARD};
const unsigned char SIGN_CODEVR[] = {_BUILD_CODEVER};

我很好奇为什么每个字符串的末尾总是有一个“$”标记。首先，我想，一旦我用“{”和“}”声明了一个字符串，我就应该遵循这个规则，但是下面的测试表明它仍然可以正常工作。

#include <stdio.h>
unsigned char A[] = {"ABC$"};
//unsigned char A[] = {"ABC"};
unsigned char B[] = "123";


int main()
{
    int i,j;
    
    for(i=0;i<sizeof(A);i++)
    {
        if(A[i] == '')
            printf("nulln");
        else
            printf("%cn",A[i]);
    }
    printf("n");
    for(j=0;j<sizeof(B);j++)
    {
        if(B[j] == '')
            printf("nulln");
        else
            printf("%cn",B[j]);
    }
    printf("size of A is %dn",(int)sizeof(A));
    printf("size of B is %dn",(int)sizeof(B));

    return 0;
}

所以我不确定“$”在某些情况下是否有任何特殊含义，或者它只是一个无意义的标记。

谢谢你的时间！

回答

; hello-DOS.asm - single-segment, 16-bit "hello world" program
;
; assemble with "nasm -f bin -o hi.com hello-DOS.asm"

    org  0x100        ; .com files always start 256 bytes into the segment

    ; int 21h is going to want...

    mov  dx, msg      ; the address of or message in dx
    mov  ah, 9        ; ah=9 - "print string" sub-function
    int  0x21         ; call dos services

    mov  ah, 0x4c     ; "terminate program" sub-function
    int  0x21         ; call dos services

    msg  db 'Hello, World!', 0x0d, 0x0a, '$'   ; $-terminated message