How do you access members of a struct that is defined within another struct?
Suppose we have a struct defined as:
struct FR {
size_t n;
struct FR_1{
unsigned char r;
unsigned char g;
unsigned char b;
};
};
Under visual studio 2015,writing:
struct FR x;
x.FR_1.
does not display options for FR_1 members.On the other hand,writing:
struct FR_1 y;
Says: Error,incomplete type is not allowed.
How do you deal with this kind of struct?
The sample declares the type struct FR_1, not a member of that type. Instead, try:
struct FR {
size_t n;
struct FR_1 {
unsigned char r;
unsigned char g;
unsigned char b;
} fr1;
};
FR x;
x.fr1.r = 0;
struct FR {
size_t n; // < Declaration of member variable
struct FR_1{ // < Declaration of nested type
unsigned char r;
unsigned char g;
unsigned char b;
};
FR_1 fr1; // < Declaration of member variable
};
You need to declare a variable of the type FR_1 in your FR structrure, not only the type itself.
FR fr;
fr.fr1.r = 0;
You need to actually create an instance of the structure. A normal struct declaration follows the form
struct struct-name {
members
} inst;
So you need to declare it as
struct FR {
size_t n;
struct FR_1 {
unsigned char r;
unsigned char g;
unsigned char b;
} fr1;
};
Now you can write
FR fr;
fr.fr1.r = 255;
. . .
