Syntax for 'new' and 'delete'?

This is a discussion on Syntax for 'new' and 'delete'? within the C++ Programming forums, part of the General Programming Boards category; I'm using Microsoft Visual C++, and for some reason, the syntax that some tutorials give me for creating new objects ...

  1. #1
    Registered User LordVirusXXP's Avatar
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    Question Syntax for 'new' and 'delete'?

    I'm using Microsoft Visual C++, and for some reason, the syntax that some tutorials give me for creating new objects and deleting them doesn't work. I've tried the following ways:

    Cat Frisky = new Cat;

    new Cat Frisky;

    Cat Frisky;
    new Frisky Fluffy;

    new Cat = Frisky;

    And none of them work. I dont know the proper syntax for this. Could someone help me out? I tried a lot of different syntax, but nothing works.
    - Dean

  2. #2
    Registered User
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    predefined class

    int * a = new int;

    user defined class, call it Cat;

    Cat * Frisky = new Cat;

    delete a;
    delete Frisky;


    new returns a pointer to the first location in memory assigned to the "new object". Note if you want a group of objects then you do this:

    Cat * kittens = new Cat[3];
    delete [] kittens;

  3. #3
    Veni Vidi Vice
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    Hmmm it seems like you have some syntax errors .

    Code:
    Cat Frisky = new Cat;
    This should work (make sure that it maches the constructors for Cat).

    Code:
    new Cat Frisky;
    Shouldn´t work. I think you mean
    Code:
    //Invokes copy-construtor
    new Cat(Frisky);
    //Make sure you store the return object in a Cat-pointer to avoid a memory leak

    Code:
    Cat Frisky;
    new Frisky Fluffy;//Se my previous explantion why not us it like this
    //New return a memory adress and should be stored in a Cat-pointer
    new Cat = Frisky;
    Try change it to
    Code:
    Cat *Frisky;
    Frisky = new Cat;
    Also make sure you are creating a console application and nothing else!

  4. #4
    Registered User LordVirusXXP's Avatar
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    Thanks guys, I guess this thread can be closed now
    - Dean

  5. #5
    &TH of undefined behavior Fordy's Avatar
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    Originally posted by LordVirusXXP
    Thanks guys, I guess this thread can be closed now
    Please dont use the link below to ask for the Mods to close this thread.......there's no need for it to be closed....you have what you want and that's great.....others can take the thread further if they wish....it will only be closed when it breaks one of the board rules (as shown at the top of each forum)

  6. #6
    Registered User LordVirusXXP's Avatar
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    My delete syntax isn't working.

    I created a new int with:

    int * a = new int;

    and now I can delete it.

    I've already tried

    delete a;

    but it doesn't work. Any suggestions?
    - Dean

  7. #7
    Skunkmeister Stoned_Coder's Avatar
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    should work so my guess is that its a scope issue and that you have lost/hidden a. show us the code.
    Free the weed!! Class B to class C is not good enough!!
    And the FAQ is here :- http://faq.cprogramming.com/cgi-bin/smartfaq.cgi

  8. #8
    Registered User LordVirusXXP's Avatar
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    You're right. I was able to create a new int before main, but it wouldn't let me delete it outside of main. I got it working now!Z Thanks.
    - Dean

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