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 1 ; Example assembly language program -- 
 2 ; Author:  karllen
 3 ; Date:    revised 5/2014
 4 
 5 .386
 6 .MODEL FLAT
 7 
 8 ExitProcess PROTO NEAR32 stdcall, dwExitCode:DWORD
 9 
10 INCLUDE io.h            ; header file for input/output
11 
12 cr      EQU     0dh     ; carriage return character
13 Lf      EQU     0ah     ; line feed
14 
15 .STACK  4096            ; reserve 4096-byte stack
16 
17 .DATA
18         promot  BYTE "Please Enter a char ",cr,Lf,0
19         answer  BYTE "The three char is "
20                 BYTE cr,Lf,0
21         befchar BYTE 1 DUP(?)
22         char    BYTE 1 DUP(?)
23       
24         aftchar BYTE 1 DUP(?)
25 .CODE
26 _start:
27         output promot
28         doWh:
29            input char,1
30            cmp   char,0d
31            je    endWh     ;只会处理最后一个字符
32         endWh:
33         mov    al,char
34         sub    al,1
35         mov    befchar,al   
36         
37         add    al,1    
38         add    al,1
39         mov    aftchar,al    
40         
41         sub    al,1  
42         mov    char,al   
43         
44         
45         output answer
46         output befchar     ;依次输出befchar char aftchar
47       
48 
49         INVOKE  ExitProcess, 0  ; exit with return code 0
50 
51 PUBLIC _start                   ; make entry point public
52 
53 END                             ; end of source code