struct

问题 How could I get an output of struct, sorted by fields? type T struct { B int A int } t := &T{B: 2, A: 1} doSomething(t) fmt.Println(t) // &{1 2} --> Sorted by fields 回答1: A struct is an ordered collection of fields. The fmt package uses reflection to get the fields and values of a struct value, and generates output in the order in which they were defined. So the simplest solution would be to declare your type where you already have your fields arranged in alphabetical order: type T struct { A

问题 I want to sort an array of pointers by Id's. However qsort fails to work because of my lack of experience with pointers. typedef struct block{ int Id; char * name; } block; typedef struct { block ** data; int size_array; } database; if( ( database = malloc(sizeof(database)) ) == NULL ) { printf("Error: malloc failed\n"); exit(EXIT_FAILURE); } if( ( database->data = malloc( sizeof( block * ) * database->size_array ) ) == NULL ) { exit(EXIT_FAILURE); } for( i = 0; i < database->size_array; i++

问题 Say I have declared a pointer to a struct and assign it with malloc() using this definition typedef struct node { int info; struct node *next; } NODE; Then somewhere in the code I declared two pointers to it NODE *node1, *node2 = NULL; node1 = malloc(sizeof(NODE)); node2 = node1; My question, should I use "free()" to release node2 just like people always do to node1 via free(node1) . What's exactly the effect of the assignment node2 = node1; Thanks. 回答1: When you do node1 = malloc(sizeof(NODE

问题 Here is the struct I am using for the nodes... typedef struct { struct Node* next; struct Node* previous; void* data; } Node; and here is the function I am using to link them void linkNodes(Node* first, Node* second) { if (first != NULL) first->next = second; if (second != NULL) second->previous = first; } now visual studio is giving me the intellisense(less) error on those lines IntelliSense: a value of type "Node *" cannot be assigned to an entity of type "Node *" can anyone explain the

问题 I have a struct with a few double values: struct A { double a; double b; } if I create a new struct, e.g. A a , are all the members (e.g. a.a ) initialized to zeroes automatically in C++? 回答1: Not by default (unless it's a variable of static storage - that is, a static or global variable). There are a few ways to initialize a struct of this kind to "zeros": A a = { 0.0, 0.0 }; A a = { }; A a = A(); or if you have a C++11 compatible compiler: A a{0.0, 0.0}; A a{} or add a constructor to the

问题 I have a c++ structure: struct a { char b; int c; int d[100]; }; The size of the struct should be 405 bytes. I saw that the size of the struct is 408 bytes. The reason is the alignment to 8 bytes after the integer "c". The array "d" should start at the 6th byte of the struct and not at the 9th byte. I used #pragma pack(1) but it didn't solve the problem. I cannot change the order of fields in the struct. Do you have any idea how can I solve this problem? Thanks! 回答1: The fault packing for

问题 Here used, unused attribute with structure. According to GCC document: unused : This attribute, attached to a variable, means that the variable is meant to be possibly unused. GCC will not produce a warning for this variable. But, In the following code, array of struct generated warning. #include <stdio.h> struct __attribute__ ((unused)) St { int x; }; void func1() { struct St s; // no warning, ok } void func2() { struct St s[1]; // Why warning??? } int main() { func1(); func2(); return 0; }

问题 This question already has answers here : How to parse/deserialize dynamic JSON (2 answers) Closed 6 months ago . I have this struct defined: type X struct { A string `json:"a_known_string"` B string `json:"b_known_string"` } This sample JSON: jsnStr := [read in from a file and printed out to confirm] It is: { "any string" : { "a_known_string" : "some value", "b_known_string" : "another value" } } If it was just the struct, I could: var x X err := json.Unmarshal(jsnStr, &x) But I need to

问题 This question already has answers here : How to parse/deserialize dynamic JSON (2 answers) Closed 6 months ago . I have this struct defined: type X struct { A string `json:"a_known_string"` B string `json:"b_known_string"` } This sample JSON: jsnStr := [read in from a file and printed out to confirm] It is: { "any string" : { "a_known_string" : "some value", "b_known_string" : "another value" } } If it was just the struct, I could: var x X err := json.Unmarshal(jsnStr, &x) But I need to

问题 I'm working on an assignment that requires me to use an " array of structs ". I did this once before for another assignment for this prof, using this code: struct monthlyData { float rainfall; float highTemp; float lowTemp; float avgTemp; } month[12]; Which got the job done fine, but I got points marked off for the array being global. What should I do instead to avoid that? I haven't touched C++ at all over the summer, so I'm pretty rusty on it at the moment and have no clue where to start