unions Questions
5
I'm hoping this isn't a duplicate question, but I've searched in some detail and haven't found my exact case before.
I have a simple struct that I also want to be able to access as a simple byte a...
1
Solved
This code is an attempt to reinterpret memory contents as a different type without violating strict aliasing rules. It was suggested as an answer to "Using std::memmove to work around strict a...
Discharge asked 20/9 at 13:37
3
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At work I've been using linux and the GCC compiler for C++11 and C++14. In some of the code at work, I've used a union to store both a reference and a pointer, as so: (Simplified to just the import...
Contrayerva asked 1/8, 2016 at 4:58
7
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How can I declare and use a C union type in Swift?
I tried:
var value: union {
var output: CLongLong
var input: [CInt]
}
but it does not work...
UPDATED: I want to use union to split a 8 by...
2
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I am trying to define a union struct with some struct and primitive members overlapping in memory with a simple array. This works perfectly in Clang and MSVC, but it doesn't compile with GCC (G++)....
Namnama asked 6/5, 2022 at 6:50
7
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I have two structures, with values that should compute a pondered average, like this simplified version:
typedef struct
{
int v_move, v_read, v_suck, v_flush, v_nop, v_call;
} values;
typedef st...
8
4
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I have built a working C library, that uses constants, in header files defined as
typedef struct Y {
union {
struct bit_field bits;
uint8_t raw[4];
} X;
} CardInfo;
static const CardInfo Y_CO...
Tab asked 19/7, 2012 at 7:16
5
I want to narrow a string to a string literal union. In other words, I want to check if the string is one of the possible values of my literal union, so that this will work (if the operator couldbe...
Buckbuckaroo asked 16/5, 2017 at 14:43
21
When should unions be used? Why do we need them?
9
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Is there an easy explanation for what this error means?
request for member '*******' in something not a structure or union
I've encountered it several times in the time that I've been learning C...
7
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let's say we have a union:
typedef union someunion {
int a;
double b;
} myunion;
Is it possible to check what type is in union after I set e.g. a=123?
My approach is to add this union to some ...
2
This seems to be similar to POD structs containing constant member, but sort of reversed.
#include <iostream>
struct A
{
int a;
};
union U
{
volatile A a;
long b;
};
int main()
{
U u1...
Enneahedron asked 5/2, 2015 at 1:53
7
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Since python is dynamically typed, of course we can do something like this:
def f(x):
return 2 if x else "s"
But is this the way python was actually intended to be used? Or in other words, do u...
Gourde asked 9/8, 2016 at 15:1
1
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In C++, unions can only have zero or one active members at any given time, and the C++ standard provides few ways to make a member active. One such way is by direct assignment in a statement like u...
3
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I have an assignment that requires me to understand what are designated initializers in C, and what it means to initialize a variable with one.
I am not familiar with the term and couldn't find any...
Conch asked 9/11, 2017 at 13:3
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I wanted to shorten my code, the code's purpose is to control stepper motors. I want to hold the ammount of steps (32 bits) and the frequency of rotation (16 bits). I receive this information throu...
6
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If I have a class:
class Odp
{
int i;
int b;
union
{
long f;
struct
{
WCHAR* pwszFoo;
HRESULT hr;
};
};
}
Union means that, of all values listed, it can only take on one of those val...
1
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Suppose sizeof( int ) == sizeof( float ), and I have the following code snippet:
union U{
int i;
float f;
};
U u1, u2;
u1.i = 1; //i is the active member of u1
u2.f = 1.0f; //f is the active mem...
Majestic asked 31/8, 2022 at 11:39
2
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Sort of related to my previous question:
Do elements of arrays count as a common initial sequence?
struct arr4 { int arr[4]; };
struct arr2 { int arr[2]; };
union U
{
arr4 _arr4;
arr2 _arr2;
}...
Rolanda asked 17/3, 2016 at 3:20
2
I was doing some experiments with unions when I encountered a problem.
union U
{
// struct flag for reverse-initialization of each byte
struct rinit_t { };
constexpr static const rinit_t rinit{}...
2
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I have an object like so:
var obj = {
key1: "apple",
key2: true,
key3: 123,
.
.
.
key{n}: ...
}
So obj can contain any number of named keys, but the values must all be either string, bool...
Mcallister asked 5/7, 2016 at 22:35
4
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Is the following undefined behaviour?
union {
int foo;
float bar;
} baz;
baz.foo = 3.14 * baz.bar;
I remember that writing and reading from the same underlying memory between two sequence ...
Blois asked 22/10, 2015 at 21:31
2
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This is a followup to a question about printing a common member from different structs
I thought that unions permit to examine the common initial sequence of two of their elements. So I ended with ...
Cinemascope asked 11/3, 2021 at 10:16
7
Solved
I'm translating a library written in C++ to C#, and the keyword 'union' exists once. In a struct.
What's the correct way of translating it into C#? And what does it do? It looks something like thi...
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