enum pointer

TucsonDon

Member
C: 
typedef struct
{
    uint8_t prow[10];
    uint8_t pcolumn[10];
    uint8_t min;
    uint8_t max;
    ModeSec_t name;
    ModeSec_t disp[6];
    PLCDMove lcd_add;
    PputsLCD lcd_dis;
    unsigned set :1;
}TextDisplayAdd_t;


I am using this structure for elements of a menu with ModeSec_t being enumeration type. I want to use a different list for a sub menu w/o having to declare a new structure and current list has 50 elements. What is the most efficient way to point to either list
 
Separate the general typedef from the instance creation; eg.

C: 
typedef struct TextStruct
{
    uint8_t prow[10];
    uint8_t pcolumn[10];
    uint8_t min;
    uint8_t max;
    ModeSec_t name;
    ModeSec_t disp[6];
    PLCDMove lcd_add;
    PputsLCD lcd_dis;
    unsigned set :1;
};

TextStruct TextDisplayAdd_t;

TextStruct TextMenu_t
 
rjenkinsgb thanks for the info. The issue that I have is ModeSec_t is a typedef'ed enum list. I want to change this to point to that list or another list w/o declaring another variable (i.e. the same variable for either list)
 
A union with pointers to both types?

You could use a void pointer, but you would need to cast it to the correct type every time it was used anywhere.
 
rjenkinsgb said:
A union with pointers to both types?

You could use a void pointer, but you would need to cast it to the correct type every time it was used anywhere.
Click to expand...
rjenkinsgb I am unsure how I need to do that, I know how to do a union, just not the way you suggest.
 
Something like:

union uptr {
TextDisplayAdd_t * txtptr;
ModeSec_t * modptr;
};

uptr.txtptr and uptr.modptr

Same memory location, but the context tells the compiler which type of data is being addressed.
 
rjenkinsgb said:
Something like:

union uptr {
TextDisplayAdd_t * txtptr;
ModeSec_t * modptr;
};

uptr.txtptr and uptr.modptr

Same memory location, but the context tells the compiler which type of data is being addressed.
Click to expand...

TextDisplayAdd_t is a structure type with ModeSec_t name and ModeSec_t disp[6] elements. ModeSec_t is an enumeration type. I want to make the array to point to ModeSec_t or another enumeration type.
 
ModeSec_t is an enumeration type. I want to make the array to point to ModeSec_t or another enumeration type.
Click to expand...
Not quite sure I follow you here, but you can't have a pointer to an enum type. You can have a pointer to a variable of type ModeSec_t, but not ModeSec_t itself.

An enum type is just another definition for an int, so it has no storage. In your structure above, 'name' and 'disp[6]' are just fancy names for integers.
 
tumbleweed thanks for the info
 
You must log in or register to reply here.

Similar threads

  • Question Question
Pointer (Oshonsoft Basic Compiler)
Replies
16
Views
7K
DogFlu66
K
  • Question Question
Better Use of Function Pointers
Replies
11
Views
6K
danadak
P
Pointer or maths more efficient?
Replies
9
Views
2K
3v0
P
Pointer confusion.
Replies
9
Views
4K
Pommie
P
S
Stack Pointer working in the assembly code
Replies
18
Views
13K
charlesli
C
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…