designated-initializer Questions

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Generally, in order to initialize a struct in c, we could only specify part of the fields. Like below: static struct fuse_operations hello_oper = { .getattr = hello_getattr, .readdir = hello_rea...
Mouflon asked 25/8, 2012 at 13:7

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Consider the following code: struct Foo{ std::string s1; std::string s2; }; int main(){ Foo f{.s1 = "s1", .s2 = f.s1 + "s2"}; std::cout << "s1='" << f...

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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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Background information about what inspired my question: I learned about Designated Initializers in C (see here and here: https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html), which are awesome...
Laoag asked 27/1, 2022 at 4:8

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I have an aggregate structure B derived from another aggregate A. I would like to initialize it and there are two options: ordinary aggregate initialization and C++20 designated initializers: struc...
Diversiform asked 7/8, 2021 at 19:25

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In the following program, aggregate struct B has the field a, which is itself an aggregate. Can C++20 designated initializer be used to set its value without surrounding curly braces? struct A { in...
Rebane asked 6/8, 2021 at 20:45

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Consider the following code: struct A{ int x; int y; }; struct B{ int y; int x; }; void func (A){ } void func (B){ } int main() { func({.y=1,.x=1}); } For some reason both clang and gcc con...
Sift asked 28/5, 2021 at 19:25

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While I was reading C++ reference, I had a question about this paragraph: Note: out-of-order designated initialization, nested designated initialization, mixing of designated initializers and r...
Sematic asked 11/11, 2018 at 15:53

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When using aggregate / designated initialization of a struct it is possible to refer to another field like this: #include <stdio.h> int main() { struct { int a; int b; } s = { .a =...
Swifter asked 12/11, 2020 at 19:1

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C++ has a nice new feature: struct Point{ int x; int y; int z; }; Point p{.x=47, .y=1701, .z=0}; But if I add a constructor then I am forbidden from using the nice designated initalizers syntax:...
Corelative asked 10/11, 2020 at 13:48

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I am unable to add init method to the following UIViewController class. I need to write some code in the init method. Do i have to write init(coder) method? Even when I add the coder and decoder me...

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static struct fuse_oprations hello_oper = { .getattr = hello_getattr, .readdir = hello_readdir, .open = hello_open, .read = hello_read, }; I don't understand this C syntax well. I can't even ...
Swadeshi asked 8/11, 2011 at 7:38

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Compiling with gcc -std=c99 -Wextra this piece of code: #include <stdio.h> struct T { int a; int *b; int c; }; int main(void) { struct T t = {.b = ((int []){1, 1})}; printf("%d\n", t...

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Having come across problems when sub-classing UIKit classes and adding immutable variables to them, I made a test project to figure out what was going on. My conclusion is that if: we have an Ob...
Mohock asked 1/7, 2015 at 12:20

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I've got a question about one of the c++20 feature, designated initializers (more info about this feature here) #include <iostream> constexpr unsigned DEFAULT_SALARY {10000}; struct Person...
Jacksnipe asked 15/11, 2019 at 11:22

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I have already stated confusion about CTAD with designated initializers in this question, but i have another confusion with a very similar code snippet template <typename int_t=int, typename fl...
Thema asked 11/9, 2019 at 9:58

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How are designated initializers (C++20) supposed to work with CTAD? This code works fine in gcc9.2, but fails with clang8 template <typename int_t=int, typename float_t=float> struct my_pai...

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Is there any specific reason why has support for designated initializers not been added to g++? Is the reason that C99 standards came late and g++ was developed earlier and later people didn't care...
Lajoie asked 4/2, 2011 at 17:5

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For a while now, one has been able to use "designated initializer" in GCC: struct CC{ double a_; double b_; }; CC cc{.a_ = 1., .b_ = 2.}; assert(cc.a_ == 1. and cc.b_ == 2.); // ok CC ...
Auston asked 11/9, 2018 at 18:39

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Here, I have initialized array like this : #include <stdio.h> int main() { int a[10] = {1, 2, 3, [7] = 4, 8, 9}; printf("a[7] = %d\na[8] = %d\na[9] = %d\n", a[7], a[8], a[9]); return ...

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I'm trying to create a simple Swift subclass of UIBarButtonItem: class LabelBarButtonItem: UIBarButtonItem { let label: UILabel init(text: String) { self.label = UILabel(frame: CGRectZero) se...
Cadmann asked 24/11, 2014 at 22:47

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I was creating my own custom tableViewCell and then I got an error saying: 'required' initializer 'init(coder:)' must be provided by subclass of 'UITableViewCell' I looked it up and obviously it'...
Wirth asked 11/1, 2017 at 17:12

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In post Using initWithNibName changes absolutely nothing, he shows two uses of the same View Nib definition, in the first case, he simply calls alloc/init and the second, he specifies initWithNibNa...

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One can use designated initializers as shown below (for "billy") without issue, but when the same initialization approach is used on dynamic memory things will break at compile-time. What are the...
Deandeana asked 16/2, 2016 at 15:30

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C99 introduced the concept of designated intializers for structs. So for example, given: typedef struct { int c; char a; float b; } X; I could initialize like: X foo = {.a = '\1', .b = 2.0F, ...
Crystallization asked 5/1, 2016 at 14:39

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