struct

问题 Suppose I have some function which returns a struct: (struct layer (points lines areas)) (define (build-new-layer height) ... (layer list-a list-b list-c)) I want to keep track of the last returned result something like: (define top-side (build-new-layer 0)) ; store the first result ... (set! top-side (build-new-layer 0.5)) ; throw away the first result and store the new one However, for that particular code I get the error: set!: assignment disallowed; cannot modify a constant constant: top

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Operator overloading in C If I have a struct: typedef struct myStruct { ... } myStruct; myStruct myStructAdd(myStruct a, myStruct b); I need something like this: #define myStruct a + myStruct b myStructAdd(a, b) // NOTE this code does NOT WORK. This is what the question is asking. To make this syntax valid: myStruct a; myStruct b; myStruct c = a + b; Is there any way to use a #define to do this? EDIT: I'm not

问题 I'm working on a practice project where the iOS app prints a list of /posts from jsonplaceholder.typicode.com, and when the user selects one a detailed view controller is loaded and further information about that post is displayed (author and number of comments). I've made three separate GET requests for the three different endpoints, as each of them require different return types and different parameters (or none at all). I wanted to take as much code as possible that's in common between the

问题 I'm trying to convert a struct and the data it contains into a legitimate JSON String. I work in Unreal Engine in C++. Struct I'm trying to convert: USTRUCT() struct DATALOGGING_API FGURaaSDataStruct { GENERATED_USTRUCT_BODY() public: UPROPERTY() FString id_session = "test"; UPROPERTY() TArray<FData> data; }; Struct that is used in the previous struct: USTRUCT() struct DATALOGGING_API FData { GENERATED_USTRUCT_BODY() public: UPROPERTY() FString data; UPROPERTY() FString tag1; UPROPERTY()

问题 In C, I have a struct with a member "frequency", which is a long unsigned int. The hardware this code is running on is 32 bits. The struct has its value set at instantiation. struct config_list configuration = { ... .frequency = (long unsigned int)5250000000u, ... } In my code, I pass this struct, via pointer, to a subroutine. Inside this subroutine, I don't seem to be able to get the right value, so to check, I put in this: printf("Config frequency: %lu\n", ptr->frequency); printf(

问题 Sorry for asking such a stupid question but I am really confused. struct Amit { int a; struct Amit *link; } *start; Here both *link and *start are used to point to a node of a linked list, but what's the difference between these two and why can't we put *start inside the structure body? 回答1: The link is a member of the structure type. Every structure of type struct Amit has one. The start is a variable of type 'pointer to struct Amit '. At any given time, there can be at most one variable

问题 I have two structs struct obj_t { int id; float x; float y; }; struct cluster_t { int size; int capacity; struct obj_t *obj; }; As you can see, there is pointer to first obj_t inside cluster_t What I want to do is to free every obj_t from array inside cluster_t Do I have to write it with for loop like this? void clear_cluster(struct cluster_t *c) { for(int i = 0; i<c->size;i++) { free(&c->obj[i]); } free(c->obj); } Or is it ok to free the memory just like this ? void clear_cluster(struct

问题 I'm developing a multiplayer api for Unity Engine. I have Room and RoomManager struct. When I want create room, I set room name, id (all of variable), after that I append this new room to allRoom array in RoomManager struct. After that when I modified to room variable, I can't change any variable. I dont know why ? Here is my structs and methods : RoomManager struct type RoomManager struct { allRooms []Room roomCounter int } Room struct type Room struct { tag string name string password

问题 I want to save data in arrays called plist . These arrays can vary in size and are part of a structure called ParticleList . I know how to create one list of size n[0] . n[0] for example is of size 2. Thus, a list of size 2. But what do I have to do, if I want to create several lists with size n[0], n[1], n[2] of type ParticleList ? To cut a long story short: How should I modify my code in order to access lists of variable size somehow like pl[numberOfList].plist[PositionInArray] = -1 or `pl

问题 I have this struct: typedef struct person_st{ char *first_name, *last_name; int id; Date birthday; }*pPerson, Person; lets say i reallocate sizeof(Person)*(++n) few times. inside each struct i also allocate space for the first_name and last_name . assuming that at some point there will be allocation failure while i use realloc , what is the safest/smartest way to handle all the first_name and last_name allocations? its there still a way to free them after the realloctaion failure of the