C++ Struct vector, Junk string value

Question

Now I'm studying vector of structs, and attempt to print it after sorting by ppid. In this process, I want to test "'the string value' is saved well", but some junk value is saved this space like below picture.

:: Second value "contest.exe" is saved well,

::but, as you see, the first value "Microsoft.VsHub~" is saved like "?(triangle)"

Why this problem occured, and how to solved it?

This is my structure,

struct process {
    string procName;
    DWORD procPid;
    DWORD procPpid;
};

main(){
    ...
    std::vector <process*> myProcess;
    ...
}

Save value like,

    process* p = new process();
    p->procName = pe32.szExeFile;
    p->procPid = pe32.th32ProcessID;
    p->procPpid = pe32.th32ParentProcessID;

    myProcess.push_back(p);

and print this

    _tprintf(TEXT("[%s]"), pe32.szExeFile);
    _tprintf(TEXT(" %s \n"), myProcess[i]);
    _tprintf(TEXT("[%d]"), myProcess[i]->procPid);

In general, avoid naked pointers in STL containers, use smart pointers instead. — Erik Alapää
– Erik Alapää, Commented Apr 11, 2016 at 12:14
In general, avoid pointers where possible. Store elements by value (std::vector<process>) instead. — Pixelchemist
– Pixelchemist, Commented Apr 11, 2016 at 12:20
@Pixelchemist - pointers are core to the language and having referring-only pointers in a vector is no problem. It's when they the vector has ownership of the pointers that issues tend to stack up. Then use whole objects/values if possible and smart pointers otherwise, the type of which should be determined by the sharing needs. — Johann Gerell
– Johann Gerell, Commented Apr 11, 2016 at 13:11
@JohannGerell: Non-ownership is when storage by value is not suitable but the code that is part of the question indicates that storing by value is probably the best choice here. Not only because a vector of values is more versatile (elements copyable, moveable, ...) but also because of performance considerations (adjacent storage, cache effects, ...) My recommendation holds. For ownership: value > smart pointer > pointer. — Pixelchemist
– Pixelchemist, Commented Apr 11, 2016 at 13:36

Johann Gerell · Accepted Answer · 2016-04-11 12:16:46Z

1

By doing

_tprintf(TEXT(" %s \n"), myProcess[i]);

you try to print the content of the process* in the myProcess vector at index i as a null terminated string. Try myProcess[i]->procName.c_str() instead.

answered Apr 11, 2016 at 12:16

Johann Gerell

25.7k11 gold badges77 silver badges128 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

송요섭 Over a year ago

Time limit will be end soon :)

Collectives™ on Stack Overflow

C++ Struct vector, Junk string value

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related