Typedef如何代替Procedural C ++的struct / class？

Question

I have to build a program(Procedural C++) that has two data types. One called Elem that is an element of a vector(single dimensional array). and One called Vector that contains an unsigned int for the size of the array and also the array of Elem's itself. I can't seem to figure out the correct way to structure these so that they work as I have never done anything with procedural c++ before.

This is what I have

typedef Elem {
    float Element;
}

typedef Vector {
    unsigned int size = 0;
    Elem* Array = new array[];
}

but I'm getting this error

C++ requires a type specifier for all declarations
typedef Elem {
~~~~~~~ ^

and also

error: expected ';' after top level declarator
typedef Elem {
            ^

I'm at a loss here, any help would be appreciated!

Answer 1

You don't say

typdef Elem {
...
};

The correct way is

struct Elem {
...
};

Note also the semicolon ; at the end of the declaration.

See also Class declaration for some small examples.

Answer 2

typedef float Elem;

struct Vector {
    unsigned int size;
    Elem* Array;
};

You may define a full-fledged Vector class with constructor, destructor, copy semantic, etc. Or just use std::vector<Elem> .

---

You might be confused by C, in which a common idiom is:

typedef struct tagVector {
    ...
} Vector;

But this verbose syntax is unnecessary in C++.