如何在C中访问结构数组中的结构成员

Question

I have an array of structs which I use to get a certain member, problem I have is that I would only like to access a particular member of a struct, not the whole struct itself. So eg if my struct is declared like this:

static _Plyr {
 char*  firstName; 
 int age; 
 char* lastName;
}

typedef struct _Plyr Player; 

and I have a table of them...e..g

static Player Table[NUM] = {
{"John", 24,  "Wall"}, 
{"Carmelo", 33,  "Anthony"}, 
....
}

I'd like to have a function that returns eg a person's last name based of their first name. So I have a *char function and I know how to get the whole struct back but I only want to get a certain member from a particular struct in this case, their last name...so I need to fix my return statement

Part of my code

char* getLastName(char* string){
 char* first;
 for (int i = 0; i < REGCOUNT; i++){
    first = Table[i].firstName;
    if (strcmp(first, str) == 0){
        return &Table[i].lastName;
    }
  }
}

I've tried Table[i].lastName, Table[i]->lastName, ...and neither seems to work. I know &Table[i] gives me the adress of the struct itself and then I can access it from there but I'd simply like to get the members themselves and not the whole struct. Thank you for your time

Answer 1

Check the below code,

typedef struct _Plyr {
    char*  firstName;
    int age;
    char* lastName;
} Player; /* typedef structure  _Plyr into  Player*/


static Player Table[] = { /* Table with NUM of items*/
        {"John", 24,  "Wall"},
        {"Carmelo", 33,  "Anthony"},
        ---------------------------
        ---------------------------
};

#define NUM (sizeof(Table)/sizeof(Player))  /* Maximum number of items in  table */


char* getLastName(char* string){
    char* first;
    for (int i = 0; i < NUM; i++){
        first = Table[i].firstName;
        if (strcmp(first, string) == 0){
            return Table[i].lastName;
        }
    }
}

Check the comments added in code.

&Table[i].lastName is not a char* , you have to return Table[i].lastName to return address of lastName .

Answer 2

you must use RegTable[i].lastName. maybe you assign the return value like this:

str = getLastName(str2);

which is wrong. you must use strcpy function like this:

strcpy(str,getLastName(str2)); 

don't forget to include if you used strcpy.