c 反彙編 迴圈結構

debug

23:     int nsum = 0

;00a572ae c7 45 f8 00
0000
00mov dword ptr [nsum],0
24: int nindex = 0
;00a572b5 c7 45 ec 00
0000
00mov dword ptr [nindex],0
25: do 
26: while(nindex <= ncount);
00a572ce 8b 45 ec mov
eax,dword ptr [nindex] 
00a572d1 3b 45
08cmp
eax,dword ptr [ncount]//先執行迴圈體，後判斷 
00a572d4 7e e6 jle
loopdo+2ch (0a572bch) 
30: return nsum;
00a572d6 8b 45 f8 mov eax,dword ptr [nsum]

34:     int nsum = 0

;00a5738e c7 45 f8 00
0000
00mov dword ptr [nsum],0
35: int nindex = 0
;00a57395 c7 45 ec 00
0000
00mov dword ptr [nindex],0
36: while (nindex <= ncount)
00a5739c 8b 45 ec mov
eax,dword ptr [nindex] 
00a5739f 3b 45
08cmp
eax,dword ptr [ncount] //先判斷，後迴圈
00a573a2 7f 14
jgloopwhile+48h (0a573b8h) 
37: 
00a573b6 eb e4 jmp
loopwhile+2ch (0a5739ch) 
41: return nsum;
00a573b8 8b 45 f8 mov eax,dword ptr [nsum]

46:     int nsum = 0

;00a5731e c7 45 f8 00
0000
00mov dword ptr [nsum],0
47: for (int nindex = 0
;nindex <= ncount; ++nindex)
00a57325 c7 45 ec 00
0000
00mov dword ptr [ebp-14h],0
//先初始化計數器變數
00a5732c eb 09
jmploopfor+37h (0a57337h)
00a5732e 8b 45 ec mov
eax,dword ptr [ebp-14h] 
00a57331
83 c0 01
add eax,1 //步長
00a57334
8945 ec mov
dword ptr [ebp-14h],eax 
00a57337 8b 45 ec mov
eax,dword ptr [ebp-14h] 
00a5733a 3b 45
08cmp
eax,dword ptr [ncount] //判斷迴圈條件
00a5733d 7f 0b
jgloopfor+4ah (0a5734ah) 
48: 
00a57348 eb e4 jmp
loopfor+2eh (0a5732eh) 
51: return nsum;
00a5734a 8b 45 f8 mov eax,dword ptr [nsum]

release

int gotodo(int ncount)

return nsum;

}printf("%d \r\n", gotodo(5));

00d01143  | 33c9            | xor ecx,ecx              | looptype.cpp:

8300d01145 | 33c0 | xor
eax,eax |
00d01147 | 03c8 | add
ecx,eax |
00d01149 | 40 | inc
eax |
00d0114a | 83f8 05 | cmp
eax,0x5 |
00d0114d | 7e f8 | jle
looptype.d01147 |
00d0114f | 51 | push
ecx |
00d01150 | 68 9401d400 | push looptype.d40194 | d40194:
"%d \r\n
"00d01155 | e8 76000000 | call
|00d0115a | 83c4 08 | add
esp,0x8 |

while(nindex <= ncount);

return nsum;

}printf("%d \r\n", loopdo(5));

00d0115d  | 33c9            | xor ecx,ecx              | looptype.cpp:

8400d0115f | 33c0 | xor
eax,eax |
00d01161 | 03c8 | add
ecx,eax |
00d01163 | 40 | inc
eax |
00d01164 | 83f8 05 | cmp
eax,0x5 |
00d01167 | 7e f8 | jle
looptype.d01161 |
00d01169 | 51 | push
ecx |
00d0116a | 68 9401d400 | push looptype.d40194 | d40194:
"%d \r\n
"00d0116f | e8 5c000000 | call
|

void dorate(int argc)

printf("%d", t);

00d011a6  | 8b55 08         | mov edx,dword ptr ss:[eb | looptype.cpp:

8800d011a9 | 83c4 08 | add esp,0x8 | looptype.cpp:
8700d011ac | 33c9 | xor ecx,ecx | 
00d011ae | 85d2 | test
edx,edx |//while優化為do···while結構，新增乙個判斷
00d011b0 | 7e 0b | jle
looptype.d011bd |
00d011b2 | 33c0 | xor eax,eax | 
00d011b4 | 8bc8 | mov ecx,eax | 
00d011b6 | 83c0 63 | add
eax,0x63 |迴圈體， *99優化為+99
00d011b9 | 3bca | cmp
ecx,edx |
00d011bb | 7c f7 |jl
looptype.d011b4 |
00d011bd | 51 | push
ecx |
00d011be | 68 9001d400 | push looptype.d40190 | d40190:"%d
"00d011c3 | e8 08000000 | call
|00d011c8 | 83c4 08 | add esp,0x8 |

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