指向const数组的int

时间:2014-08-06 11:40:35

标签: c gcc embedded pic32

我在嵌入式系统中创建了一个菜单结构,如下所示:

struct DisplayMenu
{
    short int MenuTitle;                                        // Menu title text offset - the title used in the calling menu
    char NoOfSubmenuItems;                                      // number of submenuItems in this menu ? static!
    char PositionInLastMenu;                                    // position in previous menu - helps restore previous menu screen
    struct DisplayMenu *PreviousMenu;                           // pointer to previous menu - need to be const?
    struct DisplayMenu *NextMenu[MAX_NO_OF_SUBMENU_ITEMS];      // array of pointers to submenus structs - Null if no submenu...function call instead
    void (*MenuFunctionsArray[MAX_NO_OF_SUBMENU_ITEMS])(void);  // array of function pointers - called if no submenu. Check if null
    const short int *SubMenuText;                               // pointer array of text offsets for submenu text - no set length variable length array allowed at end of struct in GCC at least
};

因为早期原型制作而被实例化:

const short int MainMenuTextStrings[]= { tSTATUS, tSETUP, tStartOfTextString, tANALYSER, tUNITS, tEndOfTextString, tUNITS, tALARM, tSCREEN, tREPORTS, tSERVICE, tStartOfTextString, tMANUAL, tAIR, tZERO, tEndOfTextString, tStartOfTextString, tMANUAL, tEndOfTextString, NULL };     // needs a new text entry

// main menu struct
struct DisplayMenu MainMenu =
{
    tMENU,                                                                                              // Menu title
    0,                                              // number of submenus
    0,                                                                                                  // no previous menu 
    NULL,                                                                                               // no previous menu to point to
    { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL },                                     // to be set up later
    { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL },                                     // function pointers
    MainMenuTextStrings
};

以便稍后初始化函数/菜单指针等

它正在使用GCC进行编译,但是当代码运行时(已启动并运行非动态菜单系统)IDE(MPLABX)正在努力查看内容MainMenu以及当我尝试运行DisplayMenuItems函数时(如下所示)我不能单步执行它

任何人都可以发现我定义结构并实例化它的方式有什么问题吗?

我计划使用以下函数使用struct显示项目:

void DisplayMenuItems(struct DisplayMenu* Menu)
{

    while(*(Menu->SubMenuText) != NULL)
    {
        if(*(Menu->SubMenuText) == tStartOfTextString)       //if a few text strings need to be concatenated on one line
        {
            while(*(Menu->SubMenuText++) != tEndOfTextString)  //keep printing until you find the EndofTextString ident
                WriteStringToDisplay((char*) &pText[Config.ucLanguage][*(Menu->SubMenuText)], SmallFont);
        }
        else /*if(*(Menu->SubMenuText) != NULL) */
        {
            WriteStringToDisplay((char*) &pText[Config.ucLanguage][*(Menu->SubMenuText)++], SmallFont);
        }
        DisplayCarriageReturn(2,SmallFont);         // try and remove this eventually? Just increment Lcd.ucLine instead
    }
}
海湾合作委员会可能会让我逃避我不应该在这里的事情,所以任何提示赞赏!

非常感谢

1 个答案:

答案 0 :(得分:2)

问题可能是你在循环中修改指针。这意味着如果第二次调用DisplayMenuItems函数,指针将不再指向MainMenuTextStrings数组,但超出它,并且访问该数据会导致undefined behavior

为什么不简单地使用数组索引语法而不是修改指针?

for (unsigned int i = 0; Menu->SubMenuText[i] != NULL; ++i)
{
    ...
}