case IDC_BUTTONDEL:
         HWND hwndcombo = GetDlgItem( hwnd, IDC_COMBOINF );
         int index = ComboBox_GetCurSel( hwndcombo );
         ComboBox_DeleteString( hwndcombo, index );
         break;

是按照杨老师的教程编的，但是总是出现一下问题:
error C2360: initialization of 'hwndcombo' is skipped by 'case' label
see declaration of 'hwndcombo'
是什么原因？急！！

你能再展出点代码吗，光凭这些代码还不能够完全说明错误的原因。
要说原因：可能是你的 hwndcombo 没有初始化，初始化被跳过，

#include "stdafx.h"
#include <windows.h>
#include <windowsx.h>
#include "resource.h"
#include "MainDlg.h"
BOOL WINAPI Main_Proc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch(uMsg)
    {
        HANDLE_MSG(hWnd, WM_INITDIALOG, Main_OnInitDialog);
        HANDLE_MSG(hWnd, WM_COMMAND, Main_OnCommand);
        HANDLE_MSG(hWnd,WM_CLOSE, Main_OnClose);
    }
    return FALSE;
}
BOOL Main_OnInitDialog(HWND hwnd, HWND hwndFocus, LPARAM lParam)
{
    return TRUE;
}
void Main_OnCommand(HWND hwnd, int id, HWND hwndCtl, UINT codeNotify)
{
   

    switch(id)
    {
        case IDC_BUTTONADD:
            TCHAR INPUT1[ 256 ];
            HWND hwndcombo = GetDlgItem( hwnd, IDC_COMBOINF );
            GetDlgItemText( hwnd, IDC_EDITADD, INPUT1, sizeof( INPUT1 ) );
            ComboBox_InsertString( hwndcombo, -1, INPUT1 );
            break;
        
        case IDC_BUTTONDEL:
            HWND hwndcombo = GetDlgItem( hwnd, IDC_COMBOINF );
            int index = ComboBox_GetCurSel( hwndcombo );
            ComboBox_DeleteString( hwndcombo, index );
            break;
        
        case IDC_BUTTONSEARCH:
            TCHAR INPUT2[ 256 ];
            HWND hwndcombo = GetDlgItem( hwnd, IDC_COMBOINF );
            GetDlgItemText( hwnd, IDC_EDITSEARCH, INPUT2, sizeof( INPUT2 ) );
            int search = ComboBox_FindStringExact( hwndcombo, -1, INPUT2 );
            ComboBox_SetCurSel( hwndcombo, search );
            break;
        
        default:
            break;
    }
}
void Main_OnClose(HWND hwnd)
{
    EndDialog(hwnd, 0);
}

对不起啊，这个我也没怎么看懂

你这个我也不懂，不过我一般找错都是把程序通读一遍，把代码的意思自己翻译一下，这样错误就容易出来了，记住要看一代码才翻译一条指令···········

switch(id)
    {
        case IDC_BUTTONADD:
        {
            TCHAR INPUT1[ 256 ];
            HWND hwndcombo = GetDlgItem( hwnd, IDC_COMBOINF );
            GetDlgItemText( hwnd, IDC_EDITADD, INPUT1, sizeof( INPUT1 ) );
            ComboBox_InsertString( hwndcombo, -1, INPUT1 );
        }
            break;
        case IDC_BUTTONDEL:
            {
                HWND hwndcombo = GetDlgItem( hwnd, IDC_COMBOINF );
                int index = ComboBox_GetCurSel( hwndcombo );
                ComboBox_DeleteString( hwndcombo, index );
            }
            break;
        
        case IDC_BUTTONSEARCH:
            {
                TCHAR INPUT2[ 256 ];
                HWND hwndcombo = GetDlgItem( hwnd, IDC_COMBOINF );
                GetDlgItemText( hwnd, IDC_EDITSEARCH, INPUT2, sizeof( INPUT2 ) );
                int search = ComboBox_FindStringExact( hwndcombo, -1, INPUT2 );
                ComboBox_SetCurSel( hwndcombo, search );
            }
            break;
        
        default:
            break;
    }