求ax2＋bx＋c＝0的根 用c语言,关于求方程ax2+bx+c=0根的问题

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#include

#include

#include

#include

#include"resource.h" BOOL CALLBACK DlgMain(HWND,UINT,WPARAM,LPARAM);

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nShowCmd)

{

DialogBox(hInstance,MAKEINTRESOURCE(IDD_DIALOG1),NULL,DlgMain);

return 0;

} BOOL CALLBACK DlgMain(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)

{

switch(message)

{

case WM_CLOSE:

{

EndDialog(hwnd,0);

return TRUE;

}

case WM_COMMAND:

{

switch(LOWORD(wParam))

{

case IDOK:

{

int a= GetDlgItemInt(hwnd,IDC_EDIT1,NULL,FALSE);

int b= GetDlgItemInt(hwnd,IDC_EDIT2,NULL,FALSE);

int c= GetDlgItemInt(hwnd,IDC_EDIT3,NULL,FALSE);

double d;

double x1,x2;

char umsg[100],t[100];

d=b*b-4*a*c;

x1=(-b+sqrt(d))/2;

x2=(-b-sqrt(d))/2;

if(d<0)

MessageBox (NULL,TEXT("方程无解"),TEXT("结果"),0);

if(d==0)

{

sprintf(umsg,_T("有两个相同的实根%.2lf"),x1);

MessageBox(NULL,TEXT(umsg), TEXT("结果"),0);

}

if(d>0)

{

sprintf(umsg,_T("有两不相同的实根%.2lf和%.2lf"),x1,x2);

MessageBox(NULL,TEXT(umsg), TEXT("结果"),0);

}

}

}

}

}

return FALSE;

}