cpp反汇编之控制结构

来源：互联网发布：linux升级ruby版本编辑：程序博客网时间：2024/05/16 09:15

控制结构主要是关于 if/else switch/case

废话不多说。。献上代码及反汇编分析。。

#include<stdio.h>int main(int argc , char *argv[]){int nInt = 9;//if(0 == nInt)__asm{cmp DWORD PTR [EBP - 4h] , 0 ;jle __exit;}//__asm{printf("%d\n" , nInt);/*push DWORD PTR [EBP - 4h];push offset string "%d\n";call printf ;add esp , 8h ; */}/*if(nInt > 9){printf("%d>9\n" , nInt);}else if(9 == nInt){printf("nInt = 9\n");}else if(8 == nInt){printf("nInt = 8\n");}*/switch(nInt){case 8 :nInt += 1; break;case 9 :nInt -= 9;break;default :nInt -= 1;break;}switch(nInt = scanf("%d" , &nInt)){case 1:printf("nInt = 1\n");break;case 2:printf("nInt = 2\n");break;case 3:printf("nInt = 3\n");break;case 5:printf("nInt = 5\n");break;case 6:printf("nInt = 6\n");break;case 7:printf("nInt = 7\n");break;case 100:printf("nInt = 100\n");break;case 400:printf("nInt = 400\n");break;case 500:printf("nInt = 500\n");break;default:break;}/*0040D76D   lea         edx,[ebp-4]0040D770   push        edx0040D771   push        offset string "%d" (0042201c)0040D776   call        scanf (0040fa20)0040D77B   add         esp,80040D77E   mov         dword ptr [ebp-4],eax0040D781   mov         eax,dword ptr [ebp-4]0040D784   mov         dword ptr [ebp-0Ch],eax0040D787   mov         ecx,dword ptr [ebp-0Ch]0040D78A   sub         ecx,1// case table index 0->max-10040D78D   mov         dword ptr [ebp-0Ch],ecx0040D790   cmp         dword ptr [ebp-0Ch],6//maxIndex0040D794   ja          __exit (0040d7f8)0040D796   mov         edx,dword ptr [ebp-0Ch]0040D799   jmp         dword ptr [edx*4+40D80Bh]//case table47:       case 1:48:           printf("nInt = 1\n");0040D7A0   push        offset string "nInt = 1\n" (00422fe0)0040D7A5   call        printf (00401070)0040D7AA   add         esp,449:           break;0040D7AD   jmp         __exit (0040d7f8)  <strong> 执行一个判断就跳转到结尾处</strong>50:       case 2:51:           printf("nInt = 2\n");0040D7AF   push        offset string "nInt = 2\n" (00422fd4)0040D7B4   call        printf (00401070)0040D7B9   add         esp,452:           break;0040D7BC   jmp         __exit (0040d7f8)53:       case 3:54:           printf("nInt = 3\n");0040D7BE   push        offset string "nInt = 3\n" (00422fc8)0040D7C3   call        printf (00401070)0040D7C8   add         esp,455:           break;0040D7CB   jmp         __exit (0040d7f8)56:       case 5:57:           printf("nInt = 5\n");0040D7CD   push        offset string "nInt = 5\n" (00422fbc)0040D7D2   call        printf (00401070)0040D7D7   add         esp,458:           break;0040D7DA   jmp         __exit (0040d7f8)59:       case 6:60:           printf("nInt = 6\n");0040D7DC   push        offset string "nInt = 6\n" (00422fb0)0040D7E1   call        printf (00401070)0040D7E6   add         esp,461:           break;0040D7E9   jmp         __exit (0040d7f8)62:       case 7:63:           printf("nInt = 7\n");0040D7EB   push        offset string "nInt = 7\n" (00422fa4)0040D7F0   call        printf (00401070)0040D7F5   add         esp,464:           break;65:       default:66:           break;67:       }68:   __exit:     69:       return 0;0040D7F8   xor         eax,eax线性结构采用数组处理,用索引来引用。

0040FAED   lea         edx,[ebp-4]0040FAF0   push        edx0040FAF1   push        offset string "%d" (0042201c)0040FAF6   call        scanf (0040fa20)0040FAFB   add         esp,80040FAFE   mov         dword ptr [ebp-4],eax0040FB01   mov         eax,dword ptr [ebp-4]0040FB04   mov         dword ptr [ebp-0Ch],eax0040FB07   cmp         dword ptr [ebp-0Ch],64h0040FB0B   jg          main+0B4h (0040fb34)0040FB0D   cmp         dword ptr [ebp-0Ch],64h#1000040FB11   je          $L554+0Fh (0040fba5)0040FB17   mov         ecx,dword ptr [ebp-0Ch]0040FB1A   sub         ecx,1#index0040FB1D   mov         dword ptr [ebp-0Ch],ecx0040FB20   cmp         dword ptr [ebp-0Ch],6#maxIndex0040FB24   ja          __exit (0040fbd0)0040FB2A   mov         edx,dword ptr [ebp-0Ch]0040FB2D   jmp         dword ptr [edx*4+40FBE3h]0040FB34   cmp         dword ptr [ebp-0Ch],190h#4000040FB3B   je          $L554+1Eh (0040fbb4)0040FB3D   cmp         dword ptr [ebp-0Ch],1F4h#5000040FB44   je          $L554+2Dh (0040fbc3)0040FB46   jmp         __exit (0040fbd0)*/switch(nInt){case 2:printf("nInt = 2\n");break;case 3:printf("nInt = 3\n");break;case 8:printf("nInt = 8\n");break;case 10:printf("nInt = 10\n");break;case 35:printf("nInt = 35\n");break;case 37:printf("nInt = 37\n");break;case 666:printf("nInt = 666\n");break;}/*非线性,有另类的就采用二叉树处理。。

/*0040FBD0   mov         eax,dword ptr [ebp-4]nInt -> eax0040FBD3   mov         dword ptr [ebp-10h],eax0040FBD6   cmp         dword ptr [ebp-10h],0Ah> 100040FBDA   jg          $L554+60h (0040fbf6)0040FBDC   cmp         dword ptr [ebp-10h],0Ah= 100040FBE0   je          $L554+0A4h (0040fc3a)0040FBE2   cmp         dword ptr [ebp-10h],20040FBE6   je          $L554+77h (0040fc0d)= 2 0040FBE8   cmp         dword ptr [ebp-10h],3= 30040FBEC   je          $L554+86h (0040fc1c)0040FBEE   cmp         dword ptr [ebp-10h],80040FBF2   je          $L554+95h (0040fc2b)=80040FBF4   jmp         __exit (0040fc74)二叉树右枝0040FBF6   cmp         dword ptr [ebp-10h],23h= 350040FBFA   je          $L554+0B3h (0040fc49)0040FBFC   cmp         dword ptr [ebp-10h],25h= 370040FC00   je          $L554+0C2h (0040fc58)0040FC02   cmp         dword ptr [ebp-10h],29Ah= 6660040FC09   je          $L554+0D1h (0040fc67)0040FC0B   jmp         __exit (0040fc74)左枝结束*/__exit:return 0;}

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