delete method and error msg

[hmm]

Subject: delete method and associated error msg
OS: w2000 pro
Compiler VC++ 6
App: Console

Error msg: DAMAGE: after Normal block[430] at 0x00300030

Hi

If I include ‘delete pName’ I receive the above error msg, but if I remove it, no error. I understood you used ‘delete’ release allocated memory i.e. prevent leakage. Am I wrong?

Thanks

hmm

Code:
#include <iostream>
#include <windows.h>
#include <fstream.h>
int main(){
// to retrive the curren user name and write to file
DWORD dwSize =30;
char *pName =new char(dwSize);


ofstream fout("C:\\temp\\user.txt",ios:ut);
if(!fout){
cout << "Unable to open file" << endl;
return 0;
}
GetUserName(pName,&dwSize);
fout.write(pName,dwSize);
// the line below causes the error
delete pName;
fout.close();


return 0;
}

[parksie]

Here's your bug:

char *pName = new char(dwSize);

That's allocating space for ONE element, giving it a value of dwSize. I expect you meant:

char *pName = new char[dwSize];

Then, you have to delete it using the delete[] operator, not the normal delete:

#include <iostream> 
#include <fstream>
#include <windows.h> 

using namespace std; // Need this to use iostream anyway!

int main() { 
    // to retrive the curren user name and write to file 
    DWORD dwSize =30; 
    char *pName = new char[dwSize]; 

    ofstream fout("C:\\temp\\user.txt");

    if(!fout){ 
        cout << "Unable to open file" << endl; 
        return -1; 
    }

    GetUserName(pName, &dwSize);

    fout << pName;

    delete[] pName;

    fout.close(); 

    return 0; 
}

You actually don't even need to use a pointer, since you know the size at compile time:

#include <iostream> 
#include <fstream>
#include <windows.h> 

using namespace std; // Need this to use iostream anyway!

int main() { 
    // to retrive the curren user name and write to file 
    DWORD dwSize =30; 
    char pName[dwSize]; 

    ofstream fout("C:\\temp\\user.txt");

    if(!fout){ 
        cout << "Unable to open file" << endl; 
        return -1; 
    }

    GetUserName(pName, &dwSize);

    fout << pName;
    fout.close(); 

    return 0;
}

Note that no delete is necessary now.

[hmm]

Thanks parksie,

Still learning!



hmm

P.S. I think I seen in one of the posts (archives), a mention of a tutorial on writing dlls written by yourself. True? If so, would you mine if I had a look at it? I could be wrong

Thanks again

[parksie]

I'll have a look for it.

Quick correction: char pName[dwSize];

Replace with: char pName[30];

[parksie]

http://www.vbforums.com/search.php?s...der=descending

[hmm]

hmm