struct

问题 I am trying to use reflection to set a pointer. elasticbeanstalk.CreateEnvironmentInput has a field SolutionStackName which is of type *string . I am getting the following error when I try to set any value: panic: reflect: call of reflect.Value.SetPointer on ptr Value Here is my code: ... newEnvCnf := new(elasticbeanstalk.CreateEnvironmentInput) checkConfig2(newEnvCnf, "SolutionStackName", "teststring") ... func checkConfig2(cnf interface{}, key string, value string) bool { log.Infof("key %v,

问题 Consider following code: #include <iostream> struct bar { double a = 1.0; int b = 2; float c = 3.0; }; void callbackFunction(int* i) { auto myStruct = reinterpret_cast<bar*>(i) - offsetof(bar, b); std::cout << myStruct->a << std::endl; std::cout << myStruct->b << std::endl; std::cout << myStruct->c << std::endl; //do stuff } int main() { bar foo; callbackFunction(&foo.b); return 0; } I have to define a callback function and I want to use some additional information in that function. I defined

问题 I have several pairs of structs for which the fields of one is a perfect superset of the other. I'd like to simulate some kind of inheritance so I don't have to have separate cases for each struct since that would almost double my code. In a language like C, I could simulate inheritance of fields with something like this: struct A { int a; }; struct B { struct A parent; int b; }; main() { struct B test1; struct A *test2 = &test1; test2->a = 7; } I want to do something like this in Rust. I

问题 I'm trying to implement a function that deletes nodes from a linked list. So far, I can delete just the first node of the list(3). I tried to go to the for loop from delete, I thought that the memory is not well allocated, I have been struggling for a few days and I don't understand, please help me a little, it's the topic I received from college. #include <stdio.h> #include <stdlib.h> typedef struct nod { int key; struct nod *urm; } NOD; NOD *first=0,*last=0; void add(int x) { NOD *p=(NOD*

问题 I'm trying to implement a function that deletes nodes from a linked list. So far, I can delete just the first node of the list(3). I tried to go to the for loop from delete, I thought that the memory is not well allocated, I have been struggling for a few days and I don't understand, please help me a little, it's the topic I received from college. #include <stdio.h> #include <stdlib.h> typedef struct nod { int key; struct nod *urm; } NOD; NOD *first=0,*last=0; void add(int x) { NOD *p=(NOD*

问题 I am using Python to convert some files to a binary format, but I've run into an odd snare. Problem Code import struct s = struct.Struct('Bffffff') print s.size Result 28 Obviously the expected size would be 25 , but it appears to be interpreting the first byte ( B ) as a 4-byte integer of some kind. It will also write out a 4-byte integer instead of a byte. Work-around A work-around exists, namely separating the B out into a separate struct , like so: Code import struct s1 = struct.Struct('B

问题 I am using Python to convert some files to a binary format, but I've run into an odd snare. Problem Code import struct s = struct.Struct('Bffffff') print s.size Result 28 Obviously the expected size would be 25 , but it appears to be interpreting the first byte ( B ) as a 4-byte integer of some kind. It will also write out a 4-byte integer instead of a byte. Work-around A work-around exists, namely separating the B out into a separate struct , like so: Code import struct s1 = struct.Struct('B

问题 If I declare a struct like this: struct { int a; char b; } ident; does that structure has a type? (i.e. an unspecified type, a default type, etc.). Instead If I declare a struct like: struct J { int a; char b; } ident; we can say that ident is a stucture variabile of type struct J . 回答1: After struct { int a; char b; } ident; ident has an “anonymous structure type” and you won’t be able to declare another variable of the same type *) . That is, two anonymous structure types are never

问题 In my project, I've defined structures so that get data from JSON. I tried to use json.Unmarshal() function. But it did not work for custom type attribute. There was a structure like this: type TestModel struct { ID NullInt `json:"id"` Name string `json:"name"` } In there, NullInt type was defined with implementations of MarshalJSON() and UnmarshalJSON() functions: // NullInt ... type NullInt struct { Int int Valid bool } // MarshalJSON ... func (ni NullInt) MarshalJSON() ([]byte, error) { if

问题 Okay this question may sound stupid to the amateur programmers . But seriously this is bothering me and a solemn answer to this doubt of mine is welcomed. I have just started to take my first ever course in data structures. And what is bothering me is this: Assuming C is used, //Implementing a node struct Node { int data; struct *Node; }; Now while creating a node why do we use the dynamic memory allocation technique where we use malloc(). Can't we just create a variable of type ' Struct Node