Struct initialization with char array outside a function

February 17, 2023

I have following typedef struct:

typedef struct
{
  E_Menus Menu;        // E_Menus is a typedef enum
  char *MenuStr[200];
  int CurrentItem;
  int ItemAmount;
  int ItemGap;
  int StartItemGap;
} T_Menu;

I want to initialize a struct of type T_Menu as a module variable (not local inside a function) as following:

char mBootMenuStr[] = {"some text"};
T_Menu mBootMenu = {eUI_BootMenu, mBootMenuStr, 1, 2, 1, 2};

But MenuStr makes me struggle. I get 2 warnings:

1    initialization of 'char *' from 'int' makes pointer from integer without a cast [-Wint-conversion] 
2    missing braces around initializer [-Wmissing-braces]

MenuStr should be a string with size 200 -> Means, the string has 200 chars.

When I remove MenuStr it builds without warnings.
What did I miss? Is it impossible to do this outside a function?

Reproducable example:

typedef enum
{
  eUI_BootMenu,
  eUI_LoginMenu,
  eUI_HomeMenu,
} E_Menus;

typedef struct
{
  E_Menus Menu;
  char *MenuStr[200];
  int CurrentItem;
  int ItemAmount;
  int ItemGap;
  int StartItemGap;
} T_Menu;

char mBootMenuStr[] = {"some text"};
T_Menu mBootMenu = {eUI_BootMenu, mBootMenuStr, 1, 2, 1, 2};

Thanks for help in advance.

>Solution :

char *MenuStr[200]; is an array of 200 pointer-to-char.

The initializer in

T_Menu mBootMenu = {eUI_BootMenu, mBootMenuStr, 1, 2, 1, 2};

is treating mBootMenuStr and each expression after it as elements to initialize that array. The integer values of 1 and 2 are being used to initialize elements of type char *, hence the warning.

GCC gives a more detailed diagnostic:

ex.c:21:49: warning: initialization of ‘char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
   21 | T_Menu mBootMenu = {eUI_BootMenu, mBootMenuStr, 1, 2, 1, 2};
      |                                                 ^
ex.c:21:49: note: (near initialization for ‘mBootMenu.MenuStr[1]’)
ex.c:21:52: warning: initialization of ‘char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
   21 | T_Menu mBootMenu = {eUI_BootMenu, mBootMenuStr, 1, 2, 1, 2};
      |                                                    ^
ex.c:21:52: note: (near initialization for ‘mBootMenu.MenuStr[2]’)
ex.c:21:55: warning: initialization of ‘char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
   21 | T_Menu mBootMenu = {eUI_BootMenu, mBootMenuStr, 1, 2, 1, 2};
      |                                                       ^
ex.c:21:55: note: (near initialization for ‘mBootMenu.MenuStr[3]’)
ex.c:21:58: warning: initialization of ‘char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
   21 | T_Menu mBootMenu = {eUI_BootMenu, mBootMenuStr, 1, 2, 1, 2};

This warning can be resolved by placing braces around mBootMenuStr, making it the sole initializing element for the MenuStr member of the structure:

T_Menu mBootMenu = {eUI_BootMenu, {mBootMenuStr}, 1, 2, 1, 2};

But it seems likely you simply wanted a string member, not an array of pointers, in the structure:

typedef struct
{
  E_Menus Menu;
  char MenuStr[200];
  int CurrentItem;
  int ItemAmount;
  int ItemGap;
  int StartItemGap;
} T_Menu;

T_Menu mBootMenu = {eUI_BootMenu, "some text", 1, 2, 1, 2};