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What does 'unsigned temp:3' means
struct Test
{
unsigned a : 5;
unsigned b : 2;
unsigned c : 1;
unsigned d : 5;
};
Test B;
printf("%u %u %u %u", B.a, B.b, B.c, B.d); // output: 0 0 0 0
static struct Test A = { 1, 2, 3, 4};
Could someone explain me what is purpose of : in struct, printf just outputs 0 so I assume these are not default values, but what they are then?
Also could someone explain me why does A.a, A.b, A.c, A.d outputs 1, 2, 1, 4 instead of 1, 2, 3, 4
209
In C programming, a struct (or structure) is a collection of variables (can be of different types) under a single name.
A struct in the C programming language (and many derivatives) is a composite data type (or record) declaration that defines a physically grouped list of variables under one name in a block of memory, allowing the different variables to be accessed via a single pointer or by the struct declared name which returns the ...
A struct variable in Golang can be copied to another variable easily using the assignment statement(=). Any changes made to the second struct will not be reflected back to the first struct.
We can also use assignment operator to make copy of struct. A lot of people don't even realize that they can copy a struct this way because one can't do same it with an array. Similarly one can return struct from a function and assign it but not array.
That is a bit field.
It basically tells the compiler that hey, this variable only needs to be x bits wide, so pack the rest of the fields in accordingly, OK?
79
These are bit-fields see this Wikipeadia section on Bitfields or this reference about bit fields
The number after the : indicates how many bits you want to reserve for the identifier on the left. This allows you to allocate less space than ordinarily would be the case by tightly packing data. You can only do this in structs or unions.
Here is a short tutorial on bit-fields.
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