CODEWITHSUNDEEP
c++arraysstructure
Frantz Paul
Frantz Paul

Reputation: 167

Difference in passing a pointer to an array of structures to a function

Is it possible to pass a pointer to an array of structures to a function? When i try this syntax, i get an error. However, if I remove the * from the function prototype and drop the & where I'm passing the structure, I do not receive an error, why is that? 

struct Last_Payment_Date        // Date Last Payment was made by customer
{
int month;
int day;
int year;
};
struct Residence                // Residence of Customer
{
string Address;
string City;
string State;
string ZIP;
};

struct Customer                 // Customer information
{
string Name;
Residence Place;
string Telephone;
int AcctBalance;
Last_Payment_Date Date;
};

void Get_Customer_Data(Customer *[], int);      // Function prototype
void Display_Customer_Data(Customer [], int);
int main()
{
const int AMT_OF_CUSTOMERS = 2;         // Amount of customers
Customer Data[AMT_OF_CUSTOMERS];

Get_Customer_Data(&Data, AMT_OF_CUSTOMERS); // ERROR!



return 0;
}

void Get_Customer_Data(Customer *[], int n)

Upvotes: 2

Views: 41

Answers (1)

Some programmer dude
Some programmer dude

Reputation: 409404

The type of e.g. &Data is not Customer *[]. The type Customer *[] is an array of pointers to Customer.

The type of &Data is Customer (*)[AMT_OF_CUSOTMERS]. I.e. it's a pointer to an array of AMT_OF_CUSTOMERS structures.

The two types are very different.

The usual way to pass arrays to a function is to let the array decay to a pointer to its first element.

Then you would instead have

void Get_Customer_Data(Customer *, int);      // Function prototype

And just call it as

Get_Customer_Data(Data, AMT_OF_CUSTOMERS);

When using Data in this way, it is the same as passing &Data[0].

Upvotes: 3

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