我已经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
};
实例化为早期原型:
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
};
以期稍后初始化功能/菜单指针等
使用GCC可以正常编译,但是当代码运行时(已经在运行非动态菜单系统),IDE(MPLABX)难以查看MainMenu的内容,而当我尝试运行DisplayMenuItems函数时(如下所示)我无法逐步解决
有人可以发现我定义结构并实例化该结构的方式有问题吗?
我计划使用以下功能来显示使用struct的项目:
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
}
}
GCC可能会让我摆脱本不该在这里碰到的东西,所以任何提示都值得赞赏!
非常感谢
问题可能出在修改循环中的指针。这意味着,如果DisplayMenuItems
第二次调用该函数,则指针将不再指向MainMenuTextStrings
数组,而是指向数组之外,并且访问该数据将导致未定义的行为。
为什么不简单地使用数组索引语法而不是修改指针?
喜欢
for (unsigned int i = 0; Menu->SubMenuText[i] != NULL; ++i)
{
...
}
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