汇编语言-比较字符串

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比较两个字符串

1. 题目：比较字符串是否相等

2. 要求：写一程序，比较两个字符串String1和String2所含的字符是否相同；若相同则显示’Match’，否则显示’No Match’。

输入两个字符串之后，将串操作所必须的寄存器等参数设置好，然后使用串操作指令进行从头到尾的比较，两个字符串相等的条件是串长度相等且对应的字符相同。

复制代码

1 ; Example assembly language program -- 
 2 ; Author: karllen
 3 ; Date:
revised 05/2014
 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
str1
BYTE 80 DUP(?)
19
str2
BYTE 80 DUP(?)
20
value
BYTE 11 DUP(?)
21 
length1 DWORD ?
22 
length2 DWORD ?
23
24
promot1 BYTE "Please Enter String1",cr,Lf,0
25
promot2 BYTE "Please Enter String2",cr,Lf,0
26
crlf
BYTE
cr,Lf,0
27
28
answerYes BYTE "Match",cr,Lf,0
29
answerNo
BYTE "No Match",cr,Lf,0
30 PUBLIC _start
; make entry point public

31 .CODE
; start of main program code

32 _start:
33 
output promot1
34
input
str1,80
35
lea
eax,str1
36
push
eax
37
call
strlen
38
add
esp,4
39
mov
length1,eax
40 
dtoa
value,eax
41 
output value
42 
output crlf
43
44 
output promot2
45
input
str2,80
46
lea
eax,str2
47
push
eax
48
call
strlen
49
add
esp,4
50
mov
length2,eax
51 
dtoa
value,eax
52 
output value
53 
output crlf
54
55
mov
edx,length2
56
;;cmp String1 and String2
57
cmp
eax,edx
;如果长度不相等
58
jne
endCMP
;则结束
59
;比较
60
lea esi,str1
61
lea edi,str2
62
mov ecx,length2
;比较的长度
63
repe cmpsb
64
jz
found
;比较成功则跳转
65
66
endCMP:
67 
output answerNo
68
jmp endMatch
69
found:
70 
output answerYes
71
;
72
endMatch:
73
74
INVOKE
ExitProcess, 0
; exit with return code 0
75
76 strlen
PROC
NEAR32
77
push
ebp
78
mov
ebp, esp
79
80
sub
eax, eax
81
mov
ebx, [ebp+8]
82 whileChar:
cmp
BYTE PTR [ebx], 0
83
je
endWhileChar
84
inc
eax
85
inc
ebx
86
jmp
whileChar
87 endWhileChar:
88
pop
ebp
89
ret
90 strlen
ENDP
91 END
; end of source code

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 1 ; Example assembly language program -- 
 2 ; Author: karllen
 3 ; Date:
revised 05/2014
 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
str1
BYTE 80 DUP(?)
19
str2
BYTE 80 DUP(?)
20
value
BYTE 11 DUP(?)
21 
length1 DWORD ?
22 
length2 DWORD ?
23
24
promot1 BYTE "Please Enter String1",cr,Lf,0
25
promot2 BYTE "Please Enter String2",cr,Lf,0
26
crlf
BYTE
cr,Lf,0
27
28
answerYes BYTE "Match",cr,Lf,0
29
answerNo
BYTE "No Match",cr,Lf,0
30 PUBLIC _start
; make entry point public

31 .CODE
; start of main program code

32 _start:
33 
output promot1
34
input
str1,80
35
lea
eax,str1
36
push
eax
37
call
strlen
38
add
esp,4
39
mov
length1,eax
40 
dtoa
value,eax
41 
output value
42 
output crlf
43
44 
output promot2
45
input
str2,80
46
lea
eax,str2
47
push
eax
48
call
strlen
49
add
esp,4
50
mov
length2,eax
51 
dtoa
value,eax
52 
output value
53 
output crlf
54
55
mov
edx,length2
56
;;cmp String1 and String2
57
cmp
eax,edx
;如果长度不相等
58
jne
endCMP
;则结束
59
;比较
60
lea esi,str1
61
lea edi,str2
62
mov ecx,length2
;比较的长度
63
repe cmpsb
64
jz
found
;比较成功则跳转
65
66
endCMP:
67 
output answerNo
68
jmp endMatch
69
found:
70 
output answerYes
71
;
72
endMatch:
73
74
INVOKE
ExitProcess, 0
; exit with return code 0
75
76 strlen
PROC
NEAR32
77
push
ebp
78
mov
ebp, esp
79
80
sub
eax, eax
81
mov
ebx, [ebp+8]
82 whileChar:
cmp
BYTE PTR [ebx], 0
83
je
endWhileChar
84
inc
eax
85
inc
ebx
86
jmp
whileChar
87 endWhileChar:
88
pop
ebp
89
ret
90 strlen
ENDP
91 END
; end of source code