C++ Object Undeclared Identifier

Question

I'm no newbie to code, but I am to Visual Studios. For the life of me, I cannot figure out why I am getting the following syntax errors. The code is refusing to allow me to declare an object Match m = new Match();.

Main.cpp

#include <iostream>
#include <string>
#include <time.h>
#include "Match.h"
#include "stdafx.h"

using namespace std;

const int NUM_TRIALS = 100000;

int main()
{
    Match m = new Match();
    printf("Program begin\n");
    for (int i = 0; i < 200; i++) {
        m = Match();
        printf("%s ... %s\n", m.to_str123().c_str(), m.printStr.c_str());
    }
    printf("Program end.\n");
    return 0;
}

Match.h

#pragma once
#ifndef MATCH_H_
#define MATCH_H_
#include <string>
#include <iostream>
#include <time.h>

using namespace std;

#define HERO_PER_TEAM 3
#define NUM_HERO 10

class Match {
public:
    Match();
    ~Match();

    string to_str123();
    string printStr();

private:
    char teams[HERO_PER_TEAM * 2];
};

#endif

Error Messages

Error   C2065   'Match': undeclared identifier  ConsoleApplication1 
Error   C2146   syntax error: missing ';' before identifier 'm' ConsoleApplication1 
Error   C2065   'm': undeclared identifier  ConsoleApplication1 
Error   C2061   syntax error: identifier 'Match'    ConsoleApplication1
Error   C2065   'm': undeclared identifier  ConsoleApplication1 
Error   C3861   'Match': identifier not found   ConsoleApplication1 
Error   C2065   'm': undeclared identifier  ConsoleApplication1 
Error   C2228   left of '.to_str123' must have class/struct/union   ConsoleApplication1 
Error   C2228   left of '.c_str' must have class/struct/union   ConsoleApplication1 
Error   C2228   left of '.printStr' must have class/struct/union    ConsoleApplication1

Use either `#pragma once` or macro include guards, not both. — Baum mit Augen, May 16 '16 at 19:35
`Match m = new Match();` --> `Match* mPtr = new Match();`. or simply `Match m;` — R Sahu, May 16 '16 at 19:37
`using namespace std;` in a header can ruin your day in many ways. Read more here: http://stackoverflow.com/questions/1452721/why-is-using-namespace-std-in-c-considered-bad-practice — user4581301, May 16 '16 at 19:42
`m.printStr.c_str()` should be `m.printStr().c_str()`. That and the pointer confusion wrap up all of the problems except the missing definition of `Match`, which I'm unable to reproduce. — user4581301, May 16 '16 at 19:49
Yes the object identifier is what is confusing the hell out of me. I rarely us VS and when I do the weirdest stuff happens to me. — Stephen Lasky, May 16 '16 at 19:59
***Error C2065 'Match': undeclared identifier ConsoleApplication1*** is caused by the following: `#include "stdafx.h"` must be the first non comment / non blank line of your cpp file. — drescherjm, May 16 '16 at 20:33

score 3 · Answer 1 · answered May 16 '16 at 19:38

3

You are using new to assign a value to a non-pointer type. If you want a pointer you can use:

Match* m = new Match();

otherwise, just declare it like this:

Match m;

Since m is not recognized as an object you are getting all of the other errors too.

Also you should be able to use #pragma once in place of standard include guards.

answered May 16 '16 at 19:38

Nathan J

195
10

Not all of the errors. `printStr` function is being used as a variable. Needs the `()`. – user4581301 May 16 '16 at 19:50
Thanks, I removed the new however I still continue to get 'Match': undeclared identifier error. – Stephen Lasky May 16 '16 at 19:53
That would indicate that the compiler can't find your class. Try what I suggested by removing the standard include guards and just using `#pragma`. – Nathan J May 16 '16 at 20:03
Yes I that as well. I have no idea what could be causing this, VS is the worst :( – Stephen Lasky May 16 '16 at 20:06
What line are you getting the undeclared identifier error on? – Nathan J May 16 '16 at 20:10
Match m = new Match(); – Stephen Lasky May 16 '16 at 20:34
That's your problem. Its `Match m;` without the parens. You only use `()` in this case when it is a non-default constructor (has arguments). Although you still would in the case of `Match* m = new Match();`. – Nathan J May 16 '16 at 21:02
Even when my main.cpp file is contains only int main() { Match m; } .. I still get the same error. – Stephen Lasky May 17 '16 at 12:19
Did you move `#include "stdafx.h"` to the first line of your cpp file? – drescherjm May 17 '16 at 14:18

score 1 · Answer 2 · answered May 16 '16 at 19:42

The new operator returns a pointer to an initialized object, using the given constructor. What you're doing here is java syntax. To do it properly you have to create a pointer to an object of that type: Match *m = new Match();. Then instead of using m.printStr you'd use m->printStr and you must not forget to delete the memory allocated using delete m. Or you could simply allocate it on the stack using Match m(); or Match m = Match(). Then you can still use the form m.printStr and you don't need to worry about deleting the memory.

C++ Object Undeclared Identifier

2 Answers2