CODEWITHSUNDEEP
c++arraysstructmemory-management
Overflowh
Overflowh

Reputation: 1114

Dynamic allocation of an array of struct

I've a trouble about this syntax.
The problem says:
calculate the histogram of occurrences of names using an array of structures allocated dynamically at runtime
I solved it in this way (I preferred to use pastebin to avoid to paste too much code here):

main.cpp http://pastebin.com/TD6Y2Acf
dinalloc.cpp http://pastebin.com/93eM9EdL
dinalloc.h http://pastebin.com/bUX7TxTs

It works, but I cannot understand why...
I declared a struct called hi and an array of this structures called vet. When, in the dinalloc.cpp I declare the function parameters, I have to wrote hi *vet. In this way, it means that I'm saying to the function to expect a pointer to an hi structure, or not? Instead, when I call the function, I give vet as parameter, that is an array of hi structures.
How it's possible that this code works?

P.S. Any advice about my code-writing method is welcome.

Upvotes: 0

Views: 554

Answers (1)

prazuber
prazuber

Reputation: 1362

Your code is correct. Actually array is a pointer to it's first element, and that's what you've got from your new operator.

Even if you had a code like 

const int n = 5;
hi vet[n];
// ...
printHistogram(vet, n);

It is still correct. According to 4.2 paragraph of the c++ standart,

An lvalue or rvalue of type “array of N T” or “array of unknown bound of T” can be converted to a prvalue of type “pointer to T”. The result is a pointer to the first element of the array.

Upvotes: 2

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