Accessing a array of Structs using pointer notation

Question

I am trying to learn C++ on my own and was trying out this. I have a struct one of whose member is an array of another structs. I have a question about alternative notation.

The structs that I have defined are

struct employeeRecordT {
    string name;
    string title;
    string ssnum;
    double salary;
    int withholding;
};

struct payrollT {
    int num;
    employeeRecordT *array;
} payroll;

I am allotting memory to payroll using the following construct

payroll.array = new employeeRecordT[payroll.num];

where payroll.num is indicating the number of elements in the array. I can access the element name of the employeeRecordT by using the array notation e.g.

payroll.array[i].title

I wanted to know how to access this using the pointer notation, I have tried

payroll.(array+i)->name = "Vikas";

and I get the following error message from g++

toy.cc:30:13: error: expected unqualified-id before '(' token toy.cc:30:14: error: 'array' was not declared in this scope

I am trying to understand what I should be using and why? Could you guys help explain.

Thanks in advance.

Regards, Vikas

badgerr · Accepted Answer · 2011-06-09 09:43:06Z

7

(payroll.array+i)->name = "Vikas";

array is a member of payroll, so when you were doing payroll.(array+i), the bracket notation (i.e. "do this first") was trying to use a variable array, and not the one within the scope of payroll.

Of course, using C++, the better solution is Neils. Use a std::vector instead of your own dynamically allocated storage if possible.

edited Jun 9, 2011 at 9:43

answered Jun 9, 2011 at 9:29

badgerr

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1 Comment

vikasm Over a year ago

Tried what you were recommending and it works. I should have thought of that. In hindsight, it appears obvious. I agree with both Neil and you that I should be using vector (and in general use STL wherever possible). I was doing this just for learning.

user2100815 · Accepted Answer · 2011-06-09 09:29:45Z

5

If it hurts, don't do it. Use a std::vector of your structures instead.

answered Jun 9, 2011 at 9:29

user2100815

1 Comment

Kerrek SB Over a year ago

-1: When people bring up a really broken question which shows that they've jumped into the implementation before thinking about the design, it's all fine and well to give high-level advice. But to be fair, this was a precise and specific question with a simple direct answer, no need to sandbag the guy for asking.

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